Electrochromic window control system with radiant trigger points

ABSTRACT

A smart window controller includes circuitry configured to establish a representative model of one or more building zones based on occupancy, construction, lighting, or cooling properties of a building. A lighting control strategy is implemented for the one or more building zones based on the representative model or one or more user preferences input at a first user interface screen of an external device. Automatic operations of one or more smart windows, cooling systems, or artificial lighting systems are controlled based on trigger points associated with the lighting control strategy, and a performance level of the lighting control strategy for the one or more building zones is determined based on one or more predetermined financial metrics.

BACKGROUND Technical Field

The present disclosure is directed to control smart windows withelectrochromic (EC) coatings or automated venetian blinds.

Description of the Related Art

The demand for energy has been rising continuously and is likely tocontinue in the future. British Petroleum published a report on thecurrent status of energy in the world, which shows an increase of 2.3%in the global primary energy consumption as described in BP StatisticalReview of World Energy, 2014, the entire contents of which isincorporated herein by reference. Growth in population and theenhancement in building services and comfort levels have increased thebuilding energy consumption as described in International Energy Agency,Key World Energy Statistics 2014, the entire contents of which isincorporated herein by reference. The reduction of energy consumption inbuildings can make a significant contribution toward lowering the globaldemand for energy as described in N. B. Behmiri, J. R. Pires Manso, “Howcrude oil consumption impacts on economic growth of sub-Saharan Africa,”Int. J. Energy 54 (2013) 74-83, the entire contents of which isincorporated herein by reference.

Office buildings usually emit a high amount of internal heat gain due tohigh rates of occupancy and significant usage of equipment and lightingas described in J. Choi, A. Aziz, V. Loftness, “Investigation on theimpacts of different genders and ages on satisfaction with thermalenvironments in office buildings,” Build. Environ. 45 (2010) 1529-1535.Office workers depend on the comfortable conditions provided in thebuilding to performing their various tasks. Thus, their productivity isdirectly dependent on the comfort level provided inside the building asdescribed in A. Gasparella, G. Pernigotto, F. Cappelletti, P. Romagnoni,P. Baggio, “Analysis and modelling of window and glazing systems energyperformance for a well-insulated residential building,” Energy Build. 43(4) (2011) 1030-1037, the entire contents of which is incorporatedherein by reference. Office buildings consume a high amount of energy inthe form of space cooling/heating and lighting, equipment, waterheating, ventilation and other applications as described in H. Hens,“Thermal comfort in office buildings: two case studies commented,”Build. Environ. 44 (2009) 1399-1408, the entire contents of which isincorporated herein by reference. In a typical office building,artificial lighting and cooling/heating/equipment are considered to bemajor contributors to building energy consumption making these systemsthe best targets for energy savings as described in P. Ihm, L. Park, M.Krarti, D. Seo, “Impact of window selection on the energy performance ofresidential buildings in South Korea,” Energy Policy 44 (2012)1-9, theentire contents of which is incorporated herein by reference. TheInternational Energy Agency has indicated that in a typical officebuilding, artificial lighting consumes the bulk of the energy followedby cooling and heating operations as described in International EnergyAgency, Key World Energy Statistics 2014. Office buildings have arelatively high proportion of lighting energy consumption per unit areadue to their functional and operational requirements as described in H.Hens, “Thermal comfort in office buildings: two case studies commented,”Build. Environ. 44 (2009) 1399-1408.

In a hot climate, cooling accounts for the highest share of energyconsumption in office buildings. Internal heat gain and solar gainthrough the exterior envelope are the major contributors to the thermalload in an office building. Heat gain through windows in particularrepresents a significant component of the cooling load and consequentlya major contributor to energy consumption as described in T. Berger, C.Amann, H. Formayer, A. Korjenic, B. Pospichal, C. Neururer, R. Smutny,“Impacts of urban location and climate change upon energy demand ofoffice buildings in Vienna, Austria,” Build. Environ. 81 (2014)258-269,the entire contents of which is incorporated herein by reference. Windowglazing plays an important role in energy performance and has asignificant effect on the overall building energy consumption. Heat flowthrough a glazed window contributes to the heat gain due to incidentsolar radiation which eventually increases the cooling load as describedin M. T. Ke, C.-H. Yeh, J.-T. Jian, “Analysis of building energyconsumption parameter and energy savings measurement and verification byapplying Quest software,” Energy Build. 61 (2013) 100-107, the entirecontents of which is incorporated herein by reference. In buildings, thenet energy gain through windows depends on the thermal properties of theglazing material. Double-pane coated glass windows are used for reducingheat and energy losses. They are very effective in lowering the buildingenergy consumption by reducing the cooling load when compared withtraditional double-glazed clear glass windows. However, colored glazingreduces the admittance of daylight thereby hindering the chances ofeffective utilization of daylight integration with artificial lightingas described in H. Arsenault, M. Hebert, D. Marie-Claudie, “Effects ofglazing color type on perception of daylight quality, arousal, andswitch-on patterns of electric light in office rooms,” Build. Environ.56 (2012) 223-231, the entire contents of which is incorporated hereinby reference.

Daylight received through windows can significantly contribute to thereduction of lighting energy consumption in office buildings asdescribed in M. T. Ke, C.-H. Yeh, J.-T. Jian, “Analysis of buildingenergy consumption parameter and energy savings measurement andverification by applying Quest software,” Energy Build. 61 (2013)100-107. It is considered as a potential passive strategy for reducingthe building energy consumption and improving the visual comfort withoutany expensive operational cost and installation. Y. W. Lim, M. Z.Kandar, M. H. Ahmad, D. R. Ossen, M. A. Abdullah, “Building facadedesign for daylighting quality in typical government office building,”Build. Environ. 57 (2012) 194-204, the entire contents of which isincorporated herein by reference, is a study with the aim of evaluatingthe daylighting performance in a typical government office building inMalaysia. Based on the simulation study, they found that by changing theglazing of the windows and adding interior blinds, a significantimprovement in daylighting quantity and quality for visual comfort couldbe achieved. The amount of savings can result from changing the glazingof the window, and the study focused only on the usage of static blindswhich block a considerable amount of daylight to maintain visual comfortin the office. H. Shen, A. Tzempelikos, “Sensitivity analysis ondaylighting and energy performance of perimeter offices with automatedshading,” Build. Environ. 59(2013) 303-314, the entire contents of whichis incorporated herein by reference, investigated the impact ofdifferent shading control strategies on the building energy performanceand daylighting in an office space using year-round, transient, thermal-and lighting-integrated simulation. Interior shades were used to blocksolar radiation and improve the visual comfort by suppressing the glarefor the occupants inside the building. Four different shading controlstrategies were modeled for maximizing the daylight utilization,minimizing energy consumption, and reducing the risk of visualdiscomfort. The role of automated roller shades was also addressed inimproving the energy and visual performance in an office buildingwithout considering the impact of different glazing types.

Daylighting provides a pleasant and attractive indoor environment thatcan foster higher productivity and performance as described in P.Plympton, S. Conway, K. Epstein, “Daylighting in Schools: ImprovingStudent Performance and Health at a Price Schools Can Afford,” NationalRenewable Energy Laboratory Report, CP-550-28059, Golden, Colo., 2000,the entire contents of which is incorporated herein by reference. Withthe proper use of sensors and controllers, daylighting is capable ofreducing the electrical lighting and providing sufficient illuminancelevels inside an office space. Y. W. Wong, “Energy performance of officebuilding in Singapore,” ASHRAETrans. 94 (Part (2)) (1988) 546-559, theentire contents of which is incorporated herein by reference, describesa numerical study for an office building located in the tropical climateof Singapore city and concluded that, with proper daylight integration,the amount of energy savings can be increased by lowering the lightingexpenditure and the cooling energy consumption. D. H. W. Li, J. C. Lam,“Evaluation of lighting performance in office buildings with daylightingcontrols,” Energy Build. 33 (2001) 793-803, the entire contents of whichis incorporated herein by reference, describes a study that indicatedthat, due to the limited studies in the field of daylighting, manyarchitects and building owners are reluctant to invest in daylightingcontrol strategies.

As discussed above, the available literature shows that work has beenconducted by researchers in exploring the benefits of daylighting, butin most of these studies the visual comfort component was ignored.Visual comfort is very important in an environment where the employeeswork continuously, as it can affect the employee's productivity level.Visual comfort is created with a predetermined amount of good qualitylight and a sophisticated light distribution. Assessing visual comfortin a critical indoor environment such as an office building is achallenging task. Many parameters must be considered during thecalculations. inside an office building.

Different commercially available glazed windows were assessed and energysavings associated with each window design were identified with andwithout daylight integration. Too much daylight can provide excessiveluminance and create an uncomfortable working environment causing visualdiscomfort as described in X. Yu, Y.h. Su, H.f. Zheng, S. Riffat, “Astudy on use of miniature dielectric compound parabolic concentrator(dCPC) for daylighting control application,” Build. Environ. 74 (2014)75-85, the entire contents of which is incorporated herein by reference.Proper design considerations can be employed when selecting the glazingof the window to ensure maximum daylight with minimal glare index asdescribed in U. Berardi, T. Wang, “Daylighting in an atrium-type highperformance house,” Build. Environ. 76 (2014) 92-104, the entirecontents of which are incorporated herein by reference.

SUMMARY

In an exemplary implementation, a smart window controller includescircuitry configured to establish a representative model of one or morebuilding zones based on occupancy, construction, lighting, or coolingproperties of a building. A lighting control strategy is implemented forthe one or more building zones based on the representative model or oneor more user preferences input at a first user interface screen of anexternal device. Automatic operations of one or more smart windows,cooling systems, or artificial lighting systems are controlled based ontrigger points associated with the lighting control strategy, and aperformance level of the lighting control strategy for the one or morebuilding zones is determined based on one or more predeterminedfinancial metrics.

The foregoing general description of the illustrative embodiments andthe following detailed description thereof are merely exemplary aspectsof the teachings of this disclosure, and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of this disclosure and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic diagram of a smart window control system,according to certain embodiments;

FIG. 2 is an exemplary block diagram illustrating functionality of asmart window control system, according to certain embodiments;

FIG. 3 is an exemplary flowchart of a smart window control process,according to certain embodiments;

FIG. 4 is an exemplary illustration of user preference interface screen,according to certain embodiments;

FIG. 5 is an exemplary illustration of a priorities interface screen,according to certain embodiments;

FIG. 6 is an exemplary illustration of a warning interface screen,according to certain embodiments;

FIG. 7 is an exemplary flowchart of a zone/building model developmentprocess, according to certain embodiments;

FIG. 8 is an exemplary illustration of a building model, according tocertain embodiments;

FIG. 9 is a table of exemplary construction properties, according tocertain embodiments;

FIG. 10 is an exemplary graph of energy consumption for a building,according to certain embodiments;

FIG. 11 is an exemplary graph of input power for a lighting controlmechanism, according to certain embodiments;

FIG. 12 is an exemplary table of energy consumption based on windowtype, according to certain embodiments;

FIG. 13 is an exemplary graph of energy consumption for a building,according to certain embodiments;

FIG. 14 is an exemplary graph of monthly variation in daylight factorfor a building, according to certain embodiments;

FIG. 15 is an exemplary graph of monthly variation in glare index for abuilding, according to certain embodiments;

FIG. 16 is an exemplary graph of monthly variation in glare index for abuilding, according to certain embodiments;

FIG. 17 is an exemplary graph of a building profile, according tocertain embodiments;

FIG. 18 is an exemplary graph of energy consumption of a building,according to certain embodiments;

FIG. 19 is an exemplary illustration of building orientations, accordingto certain embodiments;

FIG. 20 is an exemplary flowchart of a control strategy determinationprocess, according to certain embodiments;

FIG. 21 is an exemplary graph of monthly variation in glare index withdaylight control, according to certain embodiments;

FIG. 22 is an exemplary graph of monthly variation in daylight factorwith daylight control, according to certain embodiments;

FIG. 23 is an exemplary graph of monthly variations in glare index withglare control, according to certain embodiments;

FIG. 24 is an exemplary graph of monthly variations in daylight factorwith glare control, according to certain embodiments;

FIG. 25 is an exemplary graph of monthly variations in glare index forsolar control and glare control, according to certain embodiments;

FIG. 26 is an exemplary graph of energy consumption with solar control,according to certain embodiments;

FIG. 27 is an exemplary graph of monthly variations in glare index forsolar control and glare control, according to certain embodiments;

FIG. 28 is an exemplary graph of energy consumption with solar control,according to certain embodiments;

FIG. 29 is an exemplary graph of monthly variations in glare index forsolar control and glare control, according to certain embodiments;

FIG. 30 is an exemplary graph of energy consumption with solar control,according to certain embodiments;

FIG. 31 is an exemplary graph of monthly variations in glare index forsolar control and glare control, according to certain embodiments;

FIG. 32 is an exemplary graph of energy consumption with solar control,according to certain embodiments;

FIG. 33 is an exemplary graph of energy consumption based on window wallratio, according to certain embodiments;

FIG. 34 is an exemplary graph of monthly variations in daylight factorwith solar control, according to certain embodiments;

FIG. 35 is an exemplary graph of monthly variations in glare index withsolar control, according to certain embodiments;

FIG. 36 is an exemplary graph of monthly variations in daylight factorwith solar control, according to certain embodiments;

FIG. 37 is a target illuminance control process, according to certainembodiments;

FIG. 38 is an illustration of a non-limiting example of controllercircuitry, according to certain embodiments;

FIG. 39 is an exemplary schematic diagram of a data processing system,according to certain embodiments; and

FIG. 40 is an exemplary schematic diagram of a processor, according tocertain embodiments.

DETAILED DESCRIPTION

In the drawings, like reference numerals designate identical orcorresponding parts throughout the several views. Further, as usedherein, the words “a,” “an” and the like generally carry a meaning of“one or more,” unless stated otherwise. The drawings are generally drawnto scale unless specified otherwise or illustrating schematic structuresor flowcharts.

Furthermore, the terms “approximately,” “approximate,” “about,” andsimilar terms generally refer to ranges that include the identifiedvalue within a margin of 20%, 10%, or preferably 5%, and any valuestherebetween.

Aspects of this disclosure are directed to a system, device, and methodfor controlling smart windows of a building. Smart windows are made ofmaterials that can be easily switched between a transparent state and astate that is opaque. The switching is done by applying an electricvoltage to the material, or by performing some other simple, oftenmechanical, operations. They can be used to regulate the flow of lightand radiant heat into or out of a building or other space. The smartwindows can include windows that have a controllable electrochromiccoating and/or automated venetian blinds.

FIG. 1 is a schematic diagram of a smart window control system 100,according to certain embodiments. The computer 110 represents at leastone computer 110 and acts as a client device that is connected to adatabase 108, a mobile device 112, a server 102, and a building 114configured with smart windows via a network 104. In someimplementations, the computer 110 is used to view current operatingconditions and settings of the building 114, such as an amount ofshading provided by the windows having the electrochromic coating and/orautomated venetian blinds, an amount of natural daylight transmittedthrough the windows, an amount of artificial light from interiorlighting systems within the building 114, projected energy and costsavings associated with the windows, and the like. A user can also inputpreferences associated with the smart window control system 100 via aninterface at the computer 110. For example, the user preferences caninclude occupancy levels of one or more zones within the building,visual comfort and energy savings priorities, and/or financial metricpriorities. Details regarding the user preferences input at the computer110 are discussed further herein.

The server 102 represents one or more servers connected to the computer110, the database 108, the mobile device 112, and the building 114 viathe network 104. According to certain embodiments, the server 102 canoperate as a controller of the smart window control system 100 andincludes processing circuitry that establishes a representative model ofone or more building zones, implements a lighting control strategy forthe one or more building zones based on the representative model and/orthe user preferences, processes received sensor data from one or moreillumination sensors installed on an interior and exterior of thebuilding 114, controls automatic operations of the smart windows,cooling systems, and/or artificial lighting systems of the building 114based on trigger points associated with the lighting control strategy,and determines a performance level of the lighting control strategy forthe building zones. By controlling the shading provided by the smartwindows of the building 114 along with operations of other buildingsystems such as the cooling and artificial lighting systems, visualcomfort of the people within the building 114 can be achieved whileincreasing an amount energy savings. Throughout the disclosure, theserver 102 can be interchangeably referred to as a controller 102.Details regarding the processes performed by the processing circuitry ofthe server 102 are discussed further herein.

The database 108 represents one or more databases connected to thecomputer 110, the server 102, the building 114, and the mobile device112 via the network 104. In some implementations, historical dataassociated with the smart window control system 100, such as historicalweather data associated with a location of the building 114, previouslyrecorded sensor data from interior and exterior illumination sensors,and operation logs for the cooling and artificial lighting systems ofthe building, can be stored in the database 108. The database 108 canalso store the user preferences that have been input at interfacescreens on the computer 110 and/or mobile device 112.

The building 114 represents one or more buildings configured withcontrollable smart windows connected to the computer 110, the server102, the database, 108, and the mobile device 112 via the network 104.The building 114 can include any type of structure with windows thathave shading properties that can be controlled by the controller 102,such as a residential building, commercial building, industrialbuilding, or any other type of building.

The smart windows of the building 114 can be electrochromic smartwindows that have a coating which preferably has a plurality of layers,such as five layers, about 1 micron thick which is deposited on theglass substrate. The electrochromic stack on the windows may includethin metallic coatings of a metal or metal oxide such as nickel ortungsten oxide sandwiched between two transparent electrical conductors.When voltage is applied between the transparent electrical conductors, adistributed electrical field is set up. This distributed electricalfield moves various coloration ions reversibly between the ion storagefilm through the ion conductor and into the electrochromic film of thewindows, which produces an effect where a glazing of the windowsswitches between a clear and transparent state to tinted state that caninclude various amounts of shading. The electrochromic windows mayoperate at low voltage power (0-10 volts DC, preferably 0.5-2V) andremain transparent across a switching range. The electrochromic windowsare also able to change optical and thermal properties of window glassdue to chemical composition of the coating on the windows. The coatingpreferably contains one or more thermoplastic plastic layers and/or athermoset plastic layer. For example, the outermost layer may be athermoset plastic layer made from a crosslinked polymer such aspolycarbonate, acrylic and/or epoxy permanently bonded to the outermostlayer metal or metal oxide layer. Based upon a given set of controltriggers, electrochromic glass can exhibit a wide range of thermal(solar heat gain coefficient) and optical (V_(t)) properties that canproduce improved operations of the glass and thus result into moreoverall energy savings. Table 1 shows characteristics of electrochromicsmart window

TABLE 1 Visible Solar Transmission Transmission U-value State of Glass(%) (%) SHGC (W/m² · K) ON State 75 64 0.73 2.4 (Bleached) OFF State 1311 0.11 (Colored)

In addition, the smart windows can be configured with controllableblinds, such as automated venetian blinds in order to control solar gainand glare in the building 114. The lighting control strategies adjustblinds on the basis of climatic criteria. Depending on the season, solarradiation that causes heat is either blocked or let in. Illuminationand/or heat sensors may be placed near the windows to measure an amountof radiation falling on the windows. The sensors are linked to thecontroller 102 via the network 104, and the controller 102 can issuecontrol signals to modify an amount of shading provided by the blinds.Table 2 shows the characteristics of automated venetian blinds for bothfully closed and fully open positions.

TABLE 2 Visible Solar Solar Transmission Transmission Heat gain State ofblinds (%) (%) coefficient Closed 8 9 0.15 Open 80 76 0.78

The controller 102 applies a lighting control strategy, such as adaylight control strategy, a glare control strategy, or a solar controlstrategy to the smart windows that address physical and visual comfortfor a space as well as energy savings. For example, in an officebuilding where occupant productivity is valued, the lighting controlstrategies are employed to provide a visually comfortable work spacewhile still achieving energy savings. Details regarding the lightingcontrol strategies are discussed further herein. In otherimplementations, the building 114 may not have smart windows but mayhave controllable systems, such as lighting and cooling systems, thatcan be modified based on an amount of light that is transmitted throughthe windows in order to maintain a comfortable environment within thebuilding.

The mobile device 112 represents one or more mobile devices connected tothe computer 110, the server 102, the building 114, and the database 108via the network 104. The network 104 represents one or more networks,such as the Internet, connecting the computer 110, the server 102, thedatabase 108, the building 114, and the mobile device 112. The network104 can also communicate via wireless networks such as WI-FI, BLUETOOTH,cellular networks including EDGE, 3G and 4G wireless cellular systems,or any other wireless form of communication that is known.

As would be understood by one of ordinary skill in the art, based on theteachings herein, the mobile device 112 or any other external devicecould also be used in the same manner as the computer 110 to input andview the reliability level and other performance specifications for thesmart window control system 100. In addition, the computer 110 andmobile device 112 can be referred to interchangeably throughout thedisclosure and can also be referred to as an external device. Detailsregarding the processes performed by the smart window control system 100are discussed further herein.

According to certain embodiments, building energy simulation may beimportant for studying the energy flow in buildings. Building simulationprograms can be effective analytical tools for constructing the buildingmodels which can used for building the energy research and evaluation ofarchitectural design. For example, DesignBuilder, DOE-2, EnergyPlus,ENER-WIN, ECOTECT, PC-Blast, Energy Quest, BSim, Energy Express, TRACE,and TRNSYS are a few of the simulation tools currently used to performenergy analysis of buildings. For example, DesignBuilder software or anyother type of executable building simulation program may be used tocarry out the energy and visual comfort analysis of a typical officebuilding with features that allow complex buildings to be modeledrapidly as described in D. B. Crawley, “Contrasting the Capabilities ofBuilding Energy Performance Simulation Programs,” US Department ofEnergy, Washington, D.C., USA, 2005, the entire contents of which isincorporated herein by reference. The building simulation program mayuse a latest EnergyPlus simulation engine to calculate the energy andvisual performance by assessing building designs. The EnergyPlusdetailed daylighting module calculates interior daylighting illuminanceand glare index and offers the freedom of using glare control andelectric lighting controls to calculate the reduction in the artificiallighting consumption for the heat balance module. The buildingsimulation program provides an interface for the calculation ofparameters which are used to assess the visual comfort such as DaylightFactor (DF), glare index and modeling of automated interior shadingcontrol. Determining the glare index at a reference point may be basedon equation (1), as described in http://www.designbuilder.co.uk/,

$\begin{matrix}{G = \frac{L_{W}^{1.6}\Omega^{0.8}}{L_{b} + {0.7\omega^{0.5}L_{W}}}} & (1)\end{matrix}$

where G=discomfort glare index; L_(w)=average luminance of the window asseen from the reference point (cd/m²); Ω=angle subtended by window;L_(b)=luminance of the background area surrounding a wall (cd/m²);ω=angle subtended by element in the window. In addition, the daylightfactor (DF) is calculated based on equation (2) as described inhttp://www.designbuilder.co.uk/,

$\begin{matrix}{{D\; F} = {\frac{E_{i}}{E_{o}} \times 100\%}} & (2)\end{matrix}$

where E_(i)=illuminance due to daylight at a point on an indoor workingplane (lux); and E_(o)=simultaneous outdoor illuminance on a horizontalplane from an unobstructed hemisphere of overcast sky (lux).

FIG. 2 is an exemplary block diagram 200 illustrating functionality ofthe smart window control system 100, according to certain embodiments.The processing circuitry of the controller 102 can execute one or moreprocesses associated with controlling an operating voltage ofelectrochromic windows to modify an amount of shading provided by thewindows in order to allow a predetermined amount of daylight to enterthe building through the windows. The controller 102 can also control anamount of shading provided by automated blinds that are installed on aninterior surface of the windows.

At block 202, optical and thermal characteristics of the smart windowsare determined and/or modified. Electrochromic smart windows are made ofelectro-powered glass, which alters transparency as a variable voltageis applied. The application of the voltage to the electrochromic smartwindows can be managed manually or automatically. The manual mode allowsthe electrical power to be switched on/off, corresponding to atinted/clear state of glass. In some implementations, the manual modecan also include multiple voltages that correspond to varied amounts oftinting. To automate the operation of the electrochromic smart windows,the controller 102 monitors received sensor data from one or moreexterior and/or interior sensors and modifies the tinting of theelectrochromic windows based on the sensor data. Exterior triggers canbe based on received sensor data from exterior illumination and/or heatsensors installed on an exterior surface of the windows and can includesolar incidence on the glazing surface. Interior triggers can be basedon received sensor data from interior illumination and/or heat sensorsinstalled inside the building and include a daylighting level and glareindex at daylight sensor.

Block 204 shows three lighting control strategies associated with theexterior and interior control triggers for the electrochromic windows.For example, a daylight control strategy uses daylighting illuminationas a valid control trigger for the electrochromic smart windows.Illumination sensors that can include photodiode sensors can detect anamount of lighting inside the building. The transmittance of the glazingon the windows can be modified to just meet a daylight illuminance setpoint at one or more of the daylighting interior illumination sensors.With a solar control strategy, shading is applied to the windows when abeam plus diffuse solar radiation incident on the window exceeds apredetermined radiation set point value. With a glare control strategy,the transmittance of the glazing on the windows can be modified when atotal daylight glare index for a building zone from all of the exteriorwindows in the zone exceeds a predetermined glare index threshold in thedaylighting input for zone. As shown in block 206, in someimplementations, automated venetian blinds can be controlled via thesolar control strategy.

At block 208, a target illuminance for each of the building zones isdetermined, which corresponds to a total amount of illumination fromboth natural (e.g., daylight) and artificial (e.g., lighting systems)lighting sources. In one implementation, the target illuminance for thezones of the building 114 is 500 Lux. In other implementations, eachzone can have an assigned target illuminance based on a functionalityassociated with the zone. For example, hallways and stairways of abuilding may have a lower target illuminance than general work spaces ofthe building 114.

At block 210, the controller 102 issues control signals to modify anamount of artificial lighting provided by the lighting systems of thebuilding 114. In some implementations, interior illuminance sensorsdetect the daylight entering the building 114 through the windows, andthe controller 102 issues a control signal to modify the fractionalinput power of artificial lighting in discrete steps. At block 212, theamount of lighting provided by the artificial lighting system is reduced(or increased) to meet the target illuminance level.

FIG. 3 is an exemplary flowchart of a smart window control process 300,according to certain embodiments. The smart window control process 300can be applied to the building 114 having electrochromic windows and/orautomated venetian blinds.

At step S302, the processing circuitry of the controller 302 performs azone/building model development process. The zone/building modeldevelopment process includes dividing the building into zones,determining construction characteristics of the zones, determiningproperties of the windows of the building 114, and generating a profilefor each of the zones of the building 114. The controller 102 can alsoidentify exterior and interior sensors associated with each of the zonesand determine an impact factor for the sensors based on one or morecriteria. Details regarding the zone/building development process arediscussed further herein.

At step S304, user preferences for the smart window control system 100are determined. In some implementations, the processing circuitry of thecontroller 102 determines the user preferences based on inputs made bythe users at one or more interface screens at the computer 110 and/ormobile device 112. For example, the interface screens allow users toinput data associated with how the zones of the building are used, suchas occupancy levels at different times of day, week, and year andfunctions of the zones. Users can also input target temperatures for thecooling systems, target illuminance levels for the artificial lightingand/or daylight entering through the windows, and other parametersassociated with building systems. The user can also input data relatedto priorities of visual comfort and/or energy savings with respect toeach of the zones of the building as well as financial goals and/ormetrics associated with the building. For example, the financial metricscan include a desired payback period for one or more building componentsthat can be achieved through operating the systems of smart windows andother systems of the building 114 in an energy-efficient manner. In someimplementations, the processing circuitry of the controller 102 canautomatically determine default values for the user preferences based onlearned trends from historical data of operating parameters forbuildings of similar size, function, and the like. In addition, theprocessing circuitry of the controller 102 uses the user preferences todetermine which lighting control strategy to implement.

FIGS. 4 and 5 are exemplary illustrations of user preference inputinterface screens, according to certain embodiments. FIG. 4 is anexemplary illustration of user preference interface screen 400 thatincludes input fields for zone, occupancy type for the zone, and daysand hours of various occupancy levels for the zone. For example, theoccupancy type of Zone 1 of the building is a “general cubicle space,”which can be one occupancy type from a group of possible selections. Insome implementations, the occupancy type has an effect on how the smartwindows are operated. For example, smart windows of zones that have anoccupancy type of “executive suite” may be operated with a higherpriority given to visual comfort than to energy savings, and the“general cubicle space” occupancy type may result in equal weightings ofenergy savings and visual comfort.

The occupancy level input for the zones can be based on an averagenumber of people that occupy the zone for a period of time, and thecontroller 102 can determine a relative importance of energy savings andvisual comfort based on the occupancy level of each of the zones. Forexample, at times where the occupancy level for the zone is high, thevisual comfort may be prioritized higher than energy savings. Inaddition, at times when the occupancy level for the zone is low, energysavings may be given a higher priority than visual comfort.

In one implementation, the occupancy levels may be associated with threelevels (low, medium, and high), but greater or fewer numbers of levelscan also be used. For the user preference interface screen 400, the userhas indicated that Zone 1 experiences a high occupancy level on Mondaythrough Friday from 0900 to 1700, a medium occupancy level on Mondaythrough Friday from 0700 to 0900 and 2000 to 2400, and a low occupancylevel at all other hours of the week. In other implementations, the userpreference interface screen 400 can also include input fields foroccupancy level based on month, season, or any other time of year. Insome implementations, the processing circuitry of the controller 102 candetermine the occupancy level of the building based on sensor datareceived from installed video cameras and/or motion sensors within eachof the zones of the building 114. For example, the processing circuitrycan determine a population density in each zone based on a number ofpeople detected in images obtained by the installed cameras.

FIG. 5 is an exemplary illustration of a priorities interface screen500, which is another type of user interface screen where a userindicates a relative importance of energy savings, visual comfort,and/or other priorities with respect to the building zones. Thepriorities interface screen 500 includes input fields for zone,occupancy level, comfort priority level, and savings priority level. Inone implementation, for Zone 1, the user selects priority levels foreach occupancy level. For example, for a high occupancy level, the userindicates that comfort and energy savings both have a medium (M)priority. For a medium occupancy level, the user indicates that comforthas a medium priority and savings has a high (H) priority. For a lowoccupancy level, the user indicates that comfort has a low priority andenergy savings has a medium priority.

In certain embodiments, the user can input other types of priorities atthe priorities interface screen. For example, the user can input comfortand energy savings priorities associated with occupancy type as well aspriorities associated with other building systems. For example, desiredtemperature, humidity, ventilation rate, and glare index threshold canbe input at the priorities interface screen 500. In someimplementations, the processing circuitry of the controller 102 canautomatically determine default values for comfort and energy savingspriorities based on learned trends from historical data of operatingparameters for buildings of similar size, function, previously inputpreferences, and the like.

Referring back to FIG. 3, at step S306, the processing circuitry of thecontroller 102 performs a control strategy determination process. Thecontrol strategy determination process includes determining a comfortscore and an energy savings score for each of the zones based on userpreferences, building/zone profiles, and current environmentalconditions. Based on the comfort score and energy savings score, theprocessing circuitry of the controller 102 determines whether toimplement the daylight control strategy, the glare control strategy, orthe solar control strategy. Details regarding the control strategydetermination process are discussed further herein.

At step S308, the controller 102 controls the smart windows of thebuilding as well as other building systems to meet a target illuminancevalue. The processing circuitry of the controller 102 determines atarget illuminance value, determines a control trigger and operatingpoints based on the light control strategy, modifies the properties ofthe smart windows in accordance with the lighting control strategy, andcontrols artificial lighting systems to compensate for an illuminationdeficit. Details regarding the control of the smart windows and otherbuilding systems are discussed further herein.

At step S310, the processing circuitry of the controller 102 determineswhether operating the smart windows of the building 114 with a currentcontrol strategy will result in one or more financial metrics being met,which can be indicative of a performance level of the smart windowcontrol system 100. In some implementations, the financial metrics caninclude a predetermined amount of cost savings over predetermined periodof time, or a predetermined simple payback period associated withoperating one or more building components. In one example, theprocessing circuitry of the controller 102 can access financial recordsassociated with the building 114 from the database 108 and can determinethe financial metrics based on the records. For example, the controller102 can use the stored financial records that indicate one or morefinancial health attributes associated with the building such asoutstanding debts and current debt repayment rate, current energy costs,and price associated with the one or more building components todetermine the payback period. In addition, the user can input a desiredpayback period at the user preference input screen 400.

Simple payback period may be based on the initial costs, i.e.incremental initial investment cost and incremental first year utilitysavings. Simple payback period (SPP) can be used to measure costeffectiveness and can be determined by dividing the cost of implementingthe energy conservation opportunities and/or operating other buildingsystems with the annual energy savings. Table 3 shows the electricitytariff in the Kingdom of Saudi Arabia issued by Saudi Electric Companyto different sectors of buildings. The energy associated with coolingthe building as well as providing artificial lighting is provided in theform of electricity.

TABLE 3 Residential and Commercial Industrial Electricity in kWh tariffin Halala/kWh tariff in Halala/kWh   1-1000 5 12 1001-2000 5 122001-3000 10 12 3001-4000 10 12 4001-5000 12 12 5001-6000 12 126001-7000 15 12 7001-8000 20 12 8001-9000 24 12  9001-10000 28 12 Over10000 30 12

An initial glass cost can be determined per square meter of glass. Forexample, a cost of double Low E and electrochromic glass used in oneimplementation is shown in Table 4. Also, the glass cost ofelectrochromic glass is shown at a market value.

TABLE 4 Double low E Specification glass EC glass Glass cost + 140 217Installation($/m²) Controls and wirings — 33 Total cost ($/m²) 140 250

Simple payback period is calculated for all the energy conservationopportunities and/or building system components. In one example, thecost of electrochromic smart glass and associated circuitry isapproximately 900 SAR/m². In addition, the cost of electricity is basedon the data received from the Saudi Arabia electricity tariff issued bySaudi Electricity Company. From the data it can be determined that 0.3Halala/kWh tariff is being paid for office buildings. Table 5 shows thesimple payback period calculations for various energy conservationimplementations and also shows whether the visual comfort criteria ismet for each of the implementations. From the analysis it is found thatby using electrochromic smart window with the daylight control strategy,large amounts of energy can be saved but without satisfying the visualcomfort criteria. When the glare control strategy is used, 17% ofbuilding energy consumption can be saved with a payback period of 6.37years.

In certain embodiments, it is found that the service life ofelectrochromic smart windows is greater than 20 years. Because of thehigh cost of electrochromic smart windows, in some implementations, theelectrochromic smart windows may be installed on just one side of thebuilding in order to improve the payback period. For example, energysavings recorded for both lighting energy consumption and cooling energyconsumption are highest when the electrochromic smart windows areinstalled in the south orientation as will be discussed further herein.The absolute difference between the cost of the electrochromic smartwindows and double low-E glass windows can be used to determine the costof installation of the smart windows, which is approximately 450 SAR/m²according to one implementation. In addition, an estimated market costof automated venetian blinds may be approximately $125/m².

TABLE 5 Lighting Cooling Total Cost of Simple Energy energy energyenergy Cost of energy payback conservation savings savings savingsVisual Area installation savings period measure (KWhr) (KWhr) (KWhr)comfort (m²) (SAR) (SAR) (Years) EC window 251,236 511,718 647,974 Not2,232 1,004,400 194,392 5.16 with daylight Achieved control EC window199,196 585,397 524,839 Achieved 2,232 1,004,400 157,452 6.37 with glarecontrol EC window 232,210 540,247 559,565 Achieved 2,232 1,004,400167,870 5.98 with solar control EC window 46,145 84,782 134,093 Achieved693 311,850 40,228 7.75 with glare control (North) EC window 45,54075,698 130,921 Achieved 423 190,350 39,277 4.84 with glare control(East) EC window 75,940 147,359 231,564 Achieved 693 311,850 69,470 4.48with glare control (South) EC window 39,888 93,260 139,573 Achieved 423190,350 41,872 4.54 with glare control (West) EC window 73,074 60,559135,536 Achieved 693 311,850 40,661 7.66 with solar control (North) ECwindow 55,109 80,745 144,187 Achieved 423 190,350 43,257 4.4 with solarcontrol in (East) EC window 80,421 143,725 237,043 Achieved 693 311,85071,113 4.38 with solar control in (South) EC window 53,614 85,185143,898 Achieved 423 190,350 43,170 4.4 with solar control in (West)Automated 185,712 345,183 454,095 Achieved 2,232 1,046,250 136,229 7.6venetian blind with solar controller

If the processing circuitry of the controller 102 determines that theone or more financial metrics are projected to be met with the currentcontrol strategy, resulting in a “yes” at step S310, then step S312 isperformed. Otherwise, if the processing circuitry of the controller 102determines that the one or more financial metrics are not projected tobe met with the current control strategy, resulting in a “no” at stepS310, then step S314 is performed.

At step S312, energy and/or cost reports associated with operation ofthe smart windows are output to the external device. The energy andcosts reports can include operation logs that indicate whetherpredetermined visual comfort criteria are achieved, sensor dataassociated with each of the building zones, energy savings data,financial metric data, and the like.

At step S314, the controller 102 outputs a warning notification to aninterface screen of the external device to warn the user that operatingwith the current control strategy and the current user preferences mayresult in one or more financial metrics not being met within apredetermined period of time. For example, FIG. 6 is an exemplaryillustration of a warning interface screen 600, according to certainembodiments. The warning interface screen 600 is output to the computer110 and/or mobile device 112 and indicates to the user how much moneyhas been saved over a predetermined period of time and that a paybackperiod of four years is not projected to be met based on currentpreferences and operation set points. The processing circuitry of thecontroller 102 can determine modified operation set points for each ofthe control strategies that allow the payback period or any otherfinancial metric to be met, which can also be shown at the warninginterface screen 600. In one implementation, the controller 102 maymodify the lighting control strategy and/or associated operational setpoints to achieve the predetermined financial criteria without inputfrom the user.

FIG. 7 is an exemplary flowchart of a zone/building model developmentprocess 700, according to certain embodiments. The zone/building modeldevelopment process is one implementation of step S302 of the smartwindow control process 300.

In one implementation, the building 114 can be a typical office buildingthat can be modeled with defining characteristics that are based onpreviously conducted surveys and studies as described in N. T.Al-Ashwal, I. M. Ismail M. Budaiwi, “Energy savings due to daylight andartificial lighting integration in office buildings in hot climate,”Int. J. Energy Environ. 2 (6) (2011) 999-1012, the entire contents ofwhich is incorporated herein by reference. In one implementationdescribed by N. T. Al-Ashwal, I. M. Ismail M. Budaiwi, “Energy savingsdue to daylight and artificial lighting integration in office buildingsin hot climate,” Int. J. Energy Environ. 2 (6) (2011) 999-1012, anaverage floor area for a typical office building is in a range of300-800 m², with rectangular building geometry. Based on survey results,the total floor area of the building model can be assumed to be 800 m²with floor-floor height of 3.7 m. In addition, based on a golden ratiorule, the dimensions for the building are set at 36 m in length and 22 min width. In one implementation, the office model can be assumed to bein a North/South orientation because of the flow of a high amount ofdaylight through the North/South orientation and keeping in mind theadvantages of passive solar heating during the winter as described in A.Roetzel, A. Tsangrassoulis, U. Dietrich, “Impact of building design andoccupancy on office comfort and energy performance in differentclimates,” Build. Environ. 71 (2014) 165-175, the entire contents ofwhich is incorporated herein by reference. Based on the ASHRAE 90.1-2010standard, the window-to-wall ratio (WWR) for the office building modelcan be assumed to be 50%. The office building model also assumes elevenfloors with the same office function throughout all zones of thebuilding.

At step S702, the processing circuitry of the controller 102 defines oneor more zones within the building 114. In some implementations, theprocessing circuitry of the controller 102 is configured to define thebuilding zones based on a layout of the building systems, such asheating/cooling systems or lighting systems. For example, the zones maybe defined based on areas controlled by particular thermostat units orlight switch panels. The zones may also be defined so that each zonearound a periphery of the building 114 includes an equal window area orwindow-to-wall ratio (WWR). In addition, the building 114 may be definedas a single zone.

FIG. 8 is an exemplary illustration of a building model 800 thatincludes nine building zones, according to certain embodiments. In someimplementations, Zones 1-4 and 6-8 are classified as perimeter zones dueto their positions around the perimeter of the building and have windowsto illuminate the zones, and Zone 5 is classified as a core zone, whichdoes not have any windows to illuminate the zone. In addition, each ofthe perimeter zones is configured with two sensors, which are daylightsensors according to one example. The daylight sensors may beillumination sensors such as photodiode sensors that detect an amount oflight inside the building 114. In other implementations, the zones areconfigured with more than two daylight sensors per zone that arepositioned at predetermined locations that are able to detect lightentering the building 114 through the windows at various timesthroughout the day. Illumination sensors can also be placed on anexterior surface of the building 114 and/or windows to detect an amountof outside brightness. The zones can also be configured with exteriorand interior thermo sensors (e.g., thermocouples, RTD) that are able todetect heat.

Each floor in the model 800 can be divided into nine zones with twolighting control sensors for each zone. In some implementations, eachsensor has the ability to measure the daylight up to a span of 7 m inlength along a perimeter wall. In one implementation, the sensors can bemounted in the ceiling with the first sensor placed 3 m away from theperimeter wall coupled to the current source and with a variableconductance corresponding to light flux. The artificial lighting unitsin a particular zone can be dimmed to a maximum of 70% by means of alight sensor depending on an availability of the daylight. A secondsensor is mounted 5 m away from the perimeter wall, and the artificiallighting units can be dimmed by 30% for each zone. The floor plan of themodel 800 with zonal distribution and the location of the light controlsensors are shown in FIG. 8. In some implementations, no sensors areused to control the artificial lighting in zone 5, which can be referredto as a core zone because an availability of daylight may beinsignificant for that zone. Operating characteristics of the HVACsystem of the model under study can be determined based on commonpractices in hot regions as described in N. T. Al-Ashwal, I. M. IsmailM. Budaiwi, “Energy savings due to daylight and artificial lightingintegration in office buildings in hot climate,” Int. J. Energy Environ.2 (6) (2011) 999-1012 and M. A. Najid, “The Impact of HVAC SystemOperation and Selection on Energy Efficiency in Office Buildings in HotClimates (MS dissertation),” Building Environmental Control SystemProgram, Department of Architectural Engineering, King Fahd Universityof Petroleum and Minerals, Saudi Arabia, 2010, the entire contents ofwhich is incorporated herein by reference.

Referring back to FIG. 7, at step S704, construction characteristics forthe building zones are determined. The controller 102 can access theconstruction characteristics associated the construction characteristicsof the building from the database 108 and determine the constructioncharacteristics for each of the zones based on how the zones are dividedwithin the building 114. For example, FIG. 9 is a table of exemplaryconstruction properties 900, according to certain embodiments. Thephysical and thermal characteristics of the exterior wall, roof andground floor, which are used in the development of the model are shown.

In addition, M. S. Al-Homoud, “Optimum thermal design of officebuildings,” Int. J. Energy Res. 21 (1997) 941-957, the entire contentsof which is incorporated herein by reference, describes an HVAC systemdesign with a highest performance for different buildings located in hotclimate conditions. In certain embodiments, a variable air volume (VAV)system was more reliable and efficient for controlling the perimeterzones where there were continuous variations in solar load and outsidetemperature. The VAV system reduces the air flow rates in the perimeterof the building and consequently lowers the energy consumption asdescribed in G. Shim, L. Song, G. Wang, “Comparison of different fancontrol strategies on variable air volume systems through simulationsand experiments,” Build. Environ. 72 (2014) 212-222, the entire contentsof which is incorporated herein by reference. In one implementation, aVAV system is used to cool the zones in the perimeter area, whereas aconstant air volume (CAV) system is used for the core zone (zone 5). Inaddition, the supply temperature at the diffuser and ventilation ratewas set according to ASHRAE 90.1-2010 standards. For example, in someaspects, the supply temperature is 14′C and the ventilation rate is0.008 m³/s/person, which is based on the number of persons and the areato be ventilated for each zone. The illumination level for the officearea (perimeter zones) is set to 500 lux based on IESNA 2011 lightingstandard as described in J. Sanjog, P. Patel, S. Karmakar, “Indoorphysical work environment: an ergonomics perspective,” Int. J. Sci. Eng.Technol. Res. 2 (3) (2013) 2278-7798, the entire contents of which isincorporated herein by reference. However, for the core zone, theillumination level is set at 300 lux because the core zone includes astaircase and mechanical room which may use a lower light level than thelight level prescribed in the lighting standards. In someimplementations, triphosphor fluorescent lamps are used to provide thepredetermined illumination level in the office building model in everyzone as described in B.-L. Ahn, C.-Y. Jang, S.-B. Leigh, S. Yoo, H.Jeong, “Effect of LED lighting on the cooling and heating loads inoffice buildings,” Appl. Energy 113 (2014) 1484-1489, the entirecontents of which is incorporated herein by reference. The displaylighting power density of the fluorescent lamp was set at 2.4 W/m2-100lux based on ASHRAE90.1-2010 and the luminaries are recessed into theceiling.

Referring back to FIG. 7, at step S706, properties of the windows in thebuilding 114 are determined. The properties of the windows can includethe type of glass that is used, a type of tinting, and whether thewindows are configured with adjustable electrochromic glass and/orautomated venetian blinds that have properties that allow the shadingprovided by the windows to be modified by the controller 102. In someembodiments, the building 114 may include both controllable andnon-controllable windows.

In one implementation, the building includes double-glazed clear glasswindows, double-glazed tinted, or low-E glazed windows. Visual andthermal characteristics of the different window types are shown in Table7. An energy and visual comfort analysis can be performed for eachglazed window individually, and based on the analysis, the best glazingwindow can be recommended to the user. In addition, daylight passingthrough the windows can be integrated with the artificial lightingsystem of the modeled building and percentage savings in the annualcooling and the total building energy consumption can be calculated. Thesimulated results of the modeled office building with a total gross areaof 8334 m², show a total building energy consumption of 2,883,729 kWh(346 kWh/m2/year). The breakdown of annual electrical energy consumptionin the modeled office building reveals that 67% (2,018,610 kWh) of thetotal energy is used for cooling (including fans), 14% (403,722 kWh) forlighting, and 18% for equipment.

TABLE 7 U-factor Glazing Type (W/m²K) SHGC VLT Double pane, clear(6/13/6 mm) 2.6 0.5 47% Double pane, bronze tinted (6/13/6 mm) 2.6 0.547% Double pane, low-E (6/13/6 mm) 1.9 0.4 44%

In certain embodiments, the processing circuitry of the controller 102can determine energy and visual comfort performance of the building 114with different types of window glazing in hot climactic conditions, suchas tinted and low-emissivity (low-E) glazings. Annual cooling energy andtotal building energy consumption can be used as indicators forevaluating and comparing the energy performance of the different typesof window glazings. The variation in the monthly energy consumption ofthe modeled office building with different types of glazed windows(clear, tinted, and low-E) is demonstrated in FIG. 10. It can be deducedfrom FIG. 10 that the peak energy occurs during the summer monthsbecause of the high demand for cooling. In addition, the maximumelectricity consumption occurs in the month of August as it is thehottest month in the year with temperatures ranging from 48 to 50° C.and relative humidity ranging from 50% to 60% as described in M. A.Najid, “The Impact of HVAC System Operation and Selection on EnergyEfficiency in Office Buildings in Hot Climates (MS dissertation),”Building Environmental Control System Program, Department ofArchitectural Engineering, King Fahd University of Petroleum andMinerals, Saudi Arabia, 2010. By contrast, the month of January may bethe coolest month with temperatures reaching as low as 6° C., resultingin significantly less demand for cooling and resulting in the minimummonthly energy consumption. For double-pane, clear glass windows,monthly energy consumption is higher because double-pane and clear glasswindows allow in more solar radiation, which affects the cooling energycomponent throughout the year but more significantly during the summerperiod. Additionally, both low-E and tinted glazed windows are veryeffective in reducing the annual cooling consumption when compared withclear-glass windows. The colored film on tinted and low-E windowsreduces a significant amount of the sun's heat, easing the load on theair conditioner.

In addition, tinted and low-E glazed windows also reduce the annualcooling energy consumption by 9% and 14%, respectively, when compared tothe cooling energy performance of double clear-glass windows.Furthermore, the annual building energy consumption saw substantialreductions of 7% and 11%, respectively, when tinted and low-E windowsare used rather than clear-glass windows. Therefore, low-E glazedwindows are effective in reducing energy consumption in office buildingssituated in hot climates without accounting for daylight integration.The high emissivity coating on low-E glazed windows absorbs the heatfrom outside, thereby reducing the solar gain and cooling cost.

In some implementations, daylight entering through the windows can beharvested to maximize energy savings while maintaining visual comfort ateach orientation within the building 114. Lighting control sensors, suchas exterior and interior illuminance and/or thermo sensors (e.g.,thermocouple, RTD sensors) positioned in the zones of the building, canmeasure daylight availability of each zone, and the control 102 can senda control signal to the artificial lighting system to dim down to apoint where a predetermined illumination level is attained for thatzone. Lighting levels can be measured at predetermined time intervalsand are can be used to determine how much the artificial lighting can bereduced. Control techniques for dimming the artificial lighting caninclude continuous lighting control, continuous OFF control and steppedcontrol. For example, the stepped control allows for the ON/OFFswitching of lighting in discrete steps according to an availability ofnatural daylight. The electric power input and light output varyseparately in equally spaced steps. The stepped control minimizes thepower input to the lights associated with the artificial lighting systemin order to balance the illumination level inside the building zones,thereby reducing the artificial lighting energy consumption. The heatemitted by artificial lighting may be reduced due to the dimming effectprovided by the lighting control, which can further reduce the internalheat gain and thereby decrease the cooling load as discussed in H.Poirazis, A. Blomsterberg, M. Wall, “Energy simulations for glazedoffice buildings in Sweden,” Energy Build. 40 (2008) 1161-1170, theentire contents of which is incorporated herein by reference. Theproposed fraction of lights which will remain ON for different reducedillumination levels is shown in FIG. 11. For example, the graph in FIG.11 illustrates that the controller 102 reduces the artificial lightingin steps and to ensure an adequate lighting level is maintainedthroughout the day.

In one implementation, the controller 102 issues a control signal toswitch ON the stepped lighting control for windows having differenttypes of glazings. FIG. 12 is an exemplary table of energy consumptionbased on window type, according to certain embodiments. The table inFIG. 12 enumerates the energy savings in the annual lighting, coolingand total consumption which results from the integrating the daylightpassing through the windows of the building with the artificial lightingsystem of the building for different types of glazed windows.

FIG. 13 is an exemplary graph of energy consumption for a building,according to certain embodiments. As shown in FIG. 13, low-E glazedwindows are most effective in reducing the total building consumption.For example, the low-E glazed windows managed to further reduce thetotal building consumption by 15.5% just by admitting daylight into thebuilding. The variation in the lighting, cooling and total energyconsumption for clear, tinted, and low-E glazed windows with thedaylight integration is shown in FIG. 13.

Visual comfort of occupants of the building for different types ofwindow glazings can be determined based on a calculated glare index anddaylight factor (DF) for the zones of the building 114 as describedpreviously with respect to equations (1) and (2). Glare refers to acondition where discomfort arises and is caused by non-uniform luminancedistribution within the visual field. Prolonged exposure to suchconditions can result in headaches and eye fatigue as described in S.G.Navada, Chandrashekara, S. Adiga, S. G. Kini, “A study on daylightintegration with thermal comfort for energy conservation in a generaloffice,” Int. J. Electr. Energy 1 (1) (2013) 18-22, the entire contentsof which is incorporated herein by reference. DF is used to assess theinternal natural lighting level as perceived on the working plane. Itcan be defined as a ratio of work plane illuminance (at a given point)to the outdoor illuminance on a horizontal plane.

In one embodiment the coating includes an outermost thermoplastic orthermoset plastic layer that has a pattern of concaves and convexes, apattern or horizontal lines and/or a pattern of concentric circlesembedded thereon. The features of the pattern are preferably in therange of 0.5-10 micron and/or 0.5-10 mm.

FIG. 14 is an exemplary graph of monthly variation in daylight factorfor a building for double-pane clear glass, double-pane tinted, andlow-E tinted windows, according to certain embodiments. The DF iscalculated by the processing circuitry of the controller 102 and isanalyzed to assess the availability of daylight in the various zones.FIG. 14 shows the DF in terms of percentage calculated on the 21st dayof every month at noon in different orientations of the building for thedifferent types glazed windows. The building with clear-glass windowshas a highest DF compared to the other glazed windows because of ahigh-visible light transmission property. For double-pane clear-glasswindows in a north orientation, the average DF is at a maximum valueduring the month of April (DF=6.4%) because of the high amount of solarradiation received during April. The high percentage of DF in allorientations with different glazed windows illustrates how the passivedaylighting can be employed to minimize the artificial lightingconsumption.

For a building with tinted and low-E glazed windows, respectively, theDF is less than 2%, which suggests that the office may not be adequatelylit with daylight and that artificial lighting may be switched ON for alonger duration in order to provide adequate lighting for occupants ofthe building. In the north orientation, the average DF for tinted glazedwindows is 33% of the value which clear glazed windows possess.Similarly, low-E windows represent 29% of the value of clear glazedwindows. A south orientation may provide a highest amount of daylightbecause of its high DF compared to other orientations. In the eastorientation, for low-E glazed windows, the maximum DF was found in themonth of February with an average value of 3.5%, showing the space to bewell lit with daylight. For the west orientation, the maximum DF duringthe month of October can have an average value of 4.3%, whereas for thesouth orientation the maximum DF occurs during December with an averageof 3%.

In one implementation, a recommended glare index value prescribed by thelighting standards for office buildings is 22 as described in A.Piccolo, F. Simone, “Effect of switchable glazing on discomfort glarefrom windows,” Build. Environ. 44 (2009) 1171-1180 and C. A. Hviid, T.R. Nielsen, S. Svendsen, “Simple tool to evaluate the impact of daylighton building energy consumption,” Solar Energy 82 (2008) 787-798, theentire contents of which are incorporated herein by reference. Thecalculated maxi-mum glare index may be based on an assumption that theoccupant would be positioned parallel to the perimeter wall and lookingtoward the window. The setting of the artificial lighting in the officebuilding may be based on the lighting standard prescribed by IESNA,which is 500 lux as described in J. Sanjog, P. Patel, S. Karmakar,“Indoor physical work environment: an ergonomics perspective,” Int. J.Sci. Eng. Technol. Res. 2 (3) (2013) 2278-7798. The illumination levelin the office model is set at 500 lux and the comfort level is assumedto be achieved when the maximum glare index falls below 22. In certainembodiments, glare index values were calculated for differentorientations, and the results are shown in the graphs of FIG. 15. Thegraphs of FIG. 15 show that the glare index values for all glazing weregreater than the comfort level (i.e., 22). Double-glazed clear-glasswindows permit a high amount of solar radiation due to the lower thermalresistance and the high visible transmittance. The bright lightgenerates an unbalanced lighting level and glare inside, which can causea glare index value to exceed a comfort threshold level for each month.

Similarly, for tinted and low-E glazed windows, a high admittance ofradiation creates visual discomfort in the interior space of thebuilding model. From the graphs in FIG. 15, it can be interpreted thatthe highly diffuse solar radiation in the north orientation creates apeak in the maximum glare index value during the summer months(April-July). The glare index for east-facing windows reaches a maximumpoint during the month of March whereas for west-facing windows thehighest level is reached during the month of December. An average valuefor the glare index in east and west orientations is approximately 24.5.The south orientation receives the highest amount of daylight during thewinter season because the sun is present for a longer duration andincreases the radiation level, thereby increasing the glare index value.

In addition, performance of automated venetian blinds can be determinedwhen the blinds are used as an interior shade in the office buildingwith low-E glazed windows. A stepped lighting control mechanism can beused to regulate the admittance of daylight through the venetian blindsand to meet the inside lighting requirements. A glare control strategycan employed to automate the movement of the blinds and allow asufficient amount of daylight without compromising the visual comfort.The controller 102 can determine the glare index based on sensor datareceived from the illuminance and/or thermo sensors in each of thebuilding zones. The automated venetian blinds can be actuated when anamount of vertical solar irradiation results in a glare index above apredetermined threshold. In some implementations, the user can input amaximum glare index value for operating the movement of the blinds as atthe user preference interface screen 400. For example, a maximum glareindex value of 22 can be used based on prescribed standards as describedin A. Piccolo, F. Simone, “Effect of switchable glazing on discomfortglare from windows,” Build. Environ. 44 (2009) 1171-1180 and C. A.Hviid, T. R. Nielsen, S. Svendsen, “Simple tool to evaluate the impactof daylight on building energy consumption,” Solar Energy 82 (2008)787-798. The blinds may remain open when the glare index is less than22. Similarly, if the glare index is greater than, the controller 102can send a signal to close the blinds.

The transmission of daylight from automated venetian blinds can be afunction of the glare index. The energy consumption for buildings withautomated interior blinds in all the orientations can be calculated andcompared with the consumption of a building with low-E windows and withdaylight integration. The analysis shows that the energy savings are lowbecause of a small fraction of reduction in the annual building energyconsumption. The addition of blinds increases the solar heat gaincoefficient by increasing the resistance toward the flow of solarradiation and decreasing the cooling energy. However, by decreasing theflow of radiation, the daylight admittance was reduced which increases aload on the artificial lighting systems.

The monthly variation in the maximum glare index with automated venetianblinds in all the orientations is shown in FIG. 16. It can be concludedthat by using the automated venetian blinds, the glare index value canbe minimized and is be pushed within the predetermined comfort thresholdlevel.

Referring back to FIG. 7, at step S708, the processing circuitry of thecontroller 102 generates a building and/or zone profile for the building114 based on the determined construction characteristics and windowproperties. The zone profile (also referred to as a model) is arepresentative model of each zone of the building that includes anoccupancy profile, a lighting profile, a cooling profile, as well as anyother parameters associated with the zones of the building 114.

In some implementations, the processing circuitry of the controller 102determines a building occupancy schedule based on the user preferencesor historical data of local practices for buildings that serve similarfunctions. For example, it may be determined that a highest occupancylevel is from 0600 until 1800, with a one-hour lunch break from 1200 to1300, and the occupancy schedule follows the same pattern for bothsummer and winter. An occupancy profile 1702 for the building users andthe schedules for different building systems are shown in FIG. 17. Inaddition, the controller 102 can also determine a holiday schedule forthe office building model based on a Gregorian calendar for the year.For example, the processing circuitry can determine that the lightingand HVAC systems in the office model are OFF on holidays, Fridays, orany other day when employees of the building do not work. Table 6 showsinput data and assumed values for the formulation of the office buildingmodel. The building model can be determined based on a weather data fileof the Kuwaiti coastal region, which may be representative of a hotclimate. In some implementations, the weather data represents hourlysolar radiation and meteorological elements for a period of one year,derived from the weather data from the 1985-2010 Climate Data Base forSaudi Arabia archives as described in “Jeddah Regional Climate CenterSouth West Asia, 2015,” Available via DIALOG.http:/jrcc.sa/climate dataobservatory sa.php, the entire contents of which is incorporated hereinby reference.

TABLE 6 Category Value Total floor area of office building model 800 m²Number of floors  11 Floor-floor height 3.7 m Gross area (m²) 8712 Grosswall area (m²) 4464 Glazing area (m²) 2232 Dimensions of the model 36 m(length), 22 m (width) Window-to-wall ratio (WWR) 50% Number of sensorsin each zone   2 Supply temperature in model 14° C. Ventilation rate0.008 m³/s/person Illumination level in the perimeter zone(s) 500 luxIllumination level in the core zone(s) 300 lux

In addition to the occupancy profile, the graph in FIG. 17 also shows acooling profile 1704 and a lighting profile 1706 for the building 114.

In addition, the building model determined by the processing circuitrycan be verified to make sure the model is stable and reliable and can belater used for further investigation into building operations asdescribed in M. K. Urbikain, J. M. Sala, “Analysis of different modelsto estimate energy savings related to windows in residential buildings,”Energy Build. 41 (2009)687-695, the entire contents of which isincorporated herein by reference. Analytical verification can beperformed by comparing an end-use energy consumption of the modeledbuilding with an actual energy consumption of a typical existing officebuilding located in a hot region as described in M. A. Najid, “TheImpact of HVAC System Operation and Selection on Energy Efficiency inOffice Buildings in Hot Climates (MS dissertation),” BuildingEnvironmental Control System Program, Department of ArchitecturalEngineering, King Fahd University of Petroleum and Minerals, SaudiArabia, 2010. The end-use energy parameters of an office building withsimilar thermal characteristics and climatic conditions to the building114 can be used to examine the accuracy of the model. For example, theactual selected building used for the verification of the building modelis located in the hot climate of Dhahran, Saudi Arabia as described inM. A. Najid, “The Impact of HVAC System Operation and Selection onEnergy Efficiency in Office Buildings in Hot Climates (MSdissertation),” Building Environmental Control System Program,Department of Architectural Engineering, King Fahd University ofPetroleum and Minerals, Saudi Arabia, 2010. The physical and thermalcharacteristics of the actual building 114 are shown in Table 8 asdescribed in M. A. Najid, “The Impact of HVAC System Operation andSelection on Energy Efficiency in Office Buildings in Hot Climates (MSdissertation),” Building Environmental Control System Program,Department of Architectural Engineering, King Fahd University ofPetroleum and Minerals, Saudi Arabia, 2010. In one implementation, thewindows of the actual building are made of double-pane clear glass. Inaddition, based on the utility bills for the actual building, it wasfound that the actual building consumes 2,989,508 kWh over the grossarea of 8400 m² as described in M. A. Najid, “The Impact of HVAC SystemOperation and Selection on Energy Efficiency in Office Buildings in HotClimates (MS dissertation),” Building Environmental Control SystemProgram, Department of Architectural Engineering, King Fahd Universityof Petroleum and Minerals, Saudi Arabia, 2010. The result shows a veryclose similarity to the end-use energy consumption parameters for boththe modeled and actual building, which is shown in FIG. 18. For example,FIG. 18 shows modeled and actual cooling energy consumption 1802,lighting energy consumption 1804, other types of energy consumption 1806as well as a modeled and actual energy signature 1808 for the building114. It can be inferred from FIG. 18 that the energy flow parameters aresimilar for both modeled and actual buildings, with a maximum deviationof below 3% in the building total energy consumption. So, it can beconcluded that the building model developed by the zone/building modeldevelopment process 700 may be sufficiently reliable for conductingfurther energy and visual comfort analysis.

TABLE 8 Building Description Location Al-Khobar, Saudi Arabia Type ofbuilding Office Plan shape Square Total Height 41 m Gross Floor Area8400 m² Gross wall area 4690 m² Window area 2040 m² Overall WWR 43.5%Type of Glazing Double glazed-clear 6/6/6 Building Orientation NorthOccupancy density 9 m²/person (ASHRAE 90.1-2001) External Walls Granitecladding cut to size 20 mm thick, concrete hollow block 150 mm thick,12.5 mm thick gypsum board, paint on gypsum board Roof 15 mm cementplaster, 200 mm thick reinforced concrete slab, asphalt tiles Floor 100mm heavyweight concrete, 25 mm mortar cement, 25 mm terrazzo Lighting(LPD) 16.65 W/m² Equipment (EPD) 9 W/m² HVAC type Packaged single zoneSupply air temperature 13° C.

The building profile can also include building orientation, which playsa role in determining times and quantities of light that pass throughwindows of the building 114. In some implementations, buildingorientation refers to a direction the building 114 faces and can beindicated by an azimuth angle of a surface relative to true north. Theorientation can also refer to a direction that a longest side of thebuilding 114 faces. The orientation of the building can be a factor inhow much sunlight is transmitted into the interior of the buildingthrough the windows.

FIG. 19 is an exemplary illustration of building orientations, accordingto certain embodiments. For example, orientation 1902 is a top view ofthe building 114 with a north orientation. The lighting energy savingsfor building facing north that is configured with electrochromic smartwindows and controlled with the solar control strategy are approximately20%, the cooling energy consumption savings are approximately 12%, andthe total building energy consumption savings are approximately 20%.

The orientation 1904 is a top view of the building 114 rotated 45° fromtrue north. The lighting energy savings for building facing north thatis configured with electrochromic smart windows and controlled with thesolar control strategy are approximately 20.5%, the cooling energyconsumption savings are approximately 11.5%, and the total buildingenergy consumption savings are approximately 18.5%.

The orientation 1906 is a top view of the building 114 rotated 90° fromtrue north, which can also be referred to as an east orientation. Thelighting energy savings for building facing north that is configuredwith electrochromic smart windows and controlled with the solar controlstrategy are approximately 22%, the cooling energy consumption savingsare approximately 10%, and the total building energy consumption savingsare approximately 18%.

Referring back to FIG. 7, at step S710, the processing circuitryidentifies sensors associated with each of the zones of the building114. As discussed previously with respect to step S702, each of thezones of the building have daylight sensors, thermo sensors, and othertypes of sensors associated with measuring conditions of the building.For example, the zones may also include humidity sensors and/orventilation rate sensors. A file that includes all of the sensors in thebuilding 114 can be tagged with the associated zone, which is stored inthe database 108.

At step S712, the processing circuitry of the controller 102 determinesan impact weighting factor for each of the sensors in the zones of thebuilding 114. In some implementations, the impact weighting factorindicates how much a given sensor may be relied based on a number offactors that can include time of day, time of year, position of thesensor, and variation in the sensor values detected at a given sensor.For example, sunlight entering through the windows may be stronger atdifferent times of the day and year. The processing circuitry of thecontroller 102 may assign higher impact weighting factors to the sensorsthat are aligned to receive a most direct beam of light from the sunbased on the positions of the sensors and the sun at a given day andtime. In some implementations, the controller 102 determines the amountof light entering the window through the windows based on a weightedaverage of all of the sensors associated with the zone or just thesensor with the highest impact weighting factor.

FIG. 20 is an exemplary flowchart of a control strategy determinationprocess 2000, according to certain embodiments. The control strategydetermination process 2000 is one implementation of step S306 of thesmart window control process 300.

At step S2022, the processing circuitry of the controller 102 determinesa comfort score associated with each of the building zones. In someimplementations, the comfort score is a score on a scale of 1 to 10, 1to 100 or any other scale and is based on the user preferences for thebuilding determined at step S304 of the smart window control process300. For example, the comfort score can be determined based on theoccupancy type, occupancy level, and/or comfort and savings prioritiesinput at the user input interface screen 400 and the priorities inputinterface screen 500. In addition, the comfort score can also be basedon the zone profile determined at the zone/building model developmentprocess 700. For example, a building zone that faces a direction thatdoes not capture very much sunlight through the windows when comparedwith other directions may have an increased comfort score because of asmaller likelihood of achieving energy savings from sunlight enteringthe building.

At step S2024, the processing circuitry of the controller 102 determinesan energy savings score associated with each of the building zones. Insome implementations, the energy savings score is a score on a scale of1 to 10, 1 to 100 or any other scale and is based on the userpreferences for the building determined at step S304 of the smart windowcontrol process 300. For example, the energy savings score can bedetermined based on the occupancy type, occupancy level, and/or comfortand savings priorities input at the user input interface screen 400 andthe priorities input interface screen 500. In addition, the energysavings score can also be based on the zone profile determined at thezone/building model development process 700. For example, a buildingzone that faces a direction that captures a lot of sunlight through thewindows when compared with other directions may have an increased energysavings score because of a larger likelihood of achieving energy savingsfrom sunlight entering the building.

At step S2026, it is determined whether the energy savings score isgreater than an energy threshold or the comfort score is less than acomfort threshold. If the energy savings score is greater than an energythreshold or the comfort score is less than a comfort threshold,resulting in a “yes” at step S2026, then step S2028 is performed.Otherwise, if the energy savings score is less than or equal to theenergy threshold and the comfort score is greater than or equal to thecomfort threshold, resulting in a “no” at step S2026, then step S2030 isperformed.

At step S2028, the controller 102 implements the daylight controlstrategy when the energy savings score is greater than the energythreshold or the comfort score is less than the comfort threshold, whichindicates that saving energy through operating the smart windows has ahigher priority than providing visual comfort to the occupants of thebuilding 114.

The daylight control strategy can be employed to modify the propertiesof electrochromic smart windows from an opaque state to a transparentstate. In some implementations, lighting energy consumption and coolingenergy consumption can be reduced when employing the daylight controlstrategy. For example, for the building 114, the lighting energyconsumption can be reduced by 25%, and the cooling energy consumptioncan be reduced by 14%, which results in a reduction in the buildingenergy consumption by 23%. Table 9 shows a comparison between the energyperformance of a base case without smart windows and electrochromicwindows smart window controlled with the daylight control strategy.

TABLE 9 Daylight Energy Base Case Control Reduction % Energy Flow (kWh)(kWh) (kWh) Reduction Lighting Energy 136,857 102,372 34,485 25consumption Cooling Energy 1,587,191 1,462,242 124,949 8 ConsumptionTotal Energy 2,174,093 1,684,371 489,722 23 consumption

Also, maximum glare index values can be determined in order to identifywhether predetermined visual comfort criteria are achieved. For example,FIG. 21 shows the variation in the maximum glare index value for boththe base case without smart windows and electrochromic smart windowcontrolled with the daylight control strategy over a period of time. Thegraph in FIG. 21 shows that for all the orientations, the glare indexvalue is exceeds the predetermined visual comfort threshold because thetransmittance through the glazing is adjusted to meet a daylightilluminance set point at a first daylight illuminance sensor within thezone. The controller 102 reduces the artificial lighting consumption butthe additional daylight entering through the windows brings inadditional brightness that produces visual discomfort to the occupantsin the building 114. Also, FIG. 22 shows variation in the daylightfactor (%) when the electrochromic smart windows are used with thedaylight control strategy. Therefore, when the daylight control strategyis used for controlling the electrochromic smart windows, total energysavings associated with both lighting energy and cooling energy areincreased, but the glare index may not be maintained below apredetermined visual comfort threshold.

Referring back to FIG. 20, at step S2030, the controller 102 implementseither the solar control strategy or the glare control strategy when theenergy savings score is less than or equal to the energy threshold orthe comfort score is greater than or equal to the comfort threshold,which indicates that saving energy through operating the smart windowshas a lower priority than providing visual comfort to the occupants ofthe building 114. In some implementations, the controller 102 maypreferentially implement the solar control strategy. However, the usermay input a preference associated with using the solar control strategyor the glare control strategy at the user input interface screen 400.

The glare control strategy can be employed to modify the properties ofelectrochromic smart windows from an opaque state to a transparent stateto modify an amount of sunlight transmitted through the smart windowsbased on a calculated glare index. In some implementations, lightingenergy consumption is reduced by 12% and cooling energy consumption isreduced by 14% in the building 114 when the glare control strategy isemployed, which results in a reduction in total building energyconsumption by approximately 17%. Table 10 shows a comparison betweenthe energy performance of a base case without smart windows andelectrochromic windows smart window controlled with the glare controlstrategy.

TABLE 10 Glare Energy Base Case Control Reduction % Energy Flow (kWh)(kWh) (kWh) Reduction Lighting Energy 136,857 120,300 16,557 12consumption Cooling Energy 1,587,191 1,372,784 214,407 14 ConsumptionTotal Energy 2,174,093 1,808,756 365,337 17 consumption

FIG. 23 shows variation in glare index values for every month in variousorientations when the glare control strategy is employed by thecontroller 102. In some implementations, the processing circuitry of thecontroller 102 compares a calculated glare index based on receivedsensor data to one or more glare index set points to determine a voltageto apply to the electrochromic smart windows to modify the amount ofshading provided by the windows.

FIG. 24 shows the average Daylight Factor (%) for various orientationswhen the electrochromic smart windows are controlled with the glarecontrol strategy. It is observed that for all orientations the glareindex value is less than the visual comfort threshold (as shown in FIG.23) because the controller 102 modifies the transmittance of the glazingto meet a predetermined glare index set point. In doing so, only apredetermined amount of daylight is transmitted through the windows,thereby reducing the lighting energy consumption and also satisfyingvisual comfort criteria for the occupants. Therefore, when the glarecontrol strategy is selected for controlling the electrochromic smartwindows of the building 114, the energy savings associated with bothlighting energy and cooling energy are increased while maintainingvisual comfort in the zones of the building 114.

The solar control strategy can be employed to modify the properties ofelectrochromic smart windows from an opaque state to a transparent stateto modify an amount of sunlight transmitted through the smart windowsbased on a calculated amount of solar radiation from the transmittedsunlight. For example, the controller 102 can modify the voltage appliedto the electrochromic smart windows based on a sum of beam solar energyplus diffuse solar energy incident on the windows. The voltage and solarradiation set points can vary based on orientation of the windows, timeof day, time of year, and other parameters that affect the amount ofradiation at the windows.

In some implementations, the processing circuitry of the controller 102can determine the voltage and radiation set points associated with thesolar control strategy based on the building and zone models developedat the zone/building model development process 700. The voltage andradiation set points are determined in order to increase energy savingsfor the building 114 as well as achieve predetermined visual comfortcriteria that can include maintaining the glare index for the buildingzones less than a predetermined visual comfort threshold.

For example, for a north orientation of the building 114, the processingcircuitry of the controller 102 determines projected solar radiationlevels at the windows for each zone of the building 114 and alsocalculates an amount of energy savings as well as a glare index for thewindows at each orientation of the building 114. In one implementation,at a solar radiation set point value of 105 W/m², the energy savings areincreased and the calculated glare index is less than the predeterminedvisual comfort threshold for all zones of the building 114. FIG. 25 isan exemplary graph of monthly variations in glare index for solarcontrol and glare control for windows having a north orientation,according to certain embodiments. Maximum glare index values are plottedat the solar set point of 105 W/m² in order to show the visual comfortcriteria is being achieved when the solar control strategy is applied tothe electrochromic smart windows.

FIG. 26 is an exemplary graph of lighting, cooling, and total energyconsumption for various solar radiation set points using the solarcontrol strategy for windows having a north orientation, according tocertain embodiments. By increasing the solar radiation value, the amountof daylight drawn into the interior spaces of the building 114 isincreased which reduces the lighting energy consumption because theamount of artificial lighting can be reduced. On the other hand, byletting in large amounts of daylight, heat gain in the space isincreased, which increases the cooling energy consumption. In someimplementations, the total energy consumption curve can be divided into3 stages associated with various set point radiation levels.

For example, a first stage can include radiation levels between 25-100W/m². In this stage, the lighting energy consumption decreases but thereis also an increase in the cooling energy consumption due extra heatgain from outside. Even though the energy consumption increases as theradiation set point increases in the first stage, the total energyconsumption is reduced because of the larger energy reduction from thereduced lighting energy consumption. In one example, at a solarradiation value of 105 W/m², the glare index is at a saturation pointfor visual comfort level, and further increases in the radiation valueresult in visual discomfort in the indoor environment.

A second stage can include radiation levels between 105-175 W/m². Inthis stage, the savings in total energy consumption may be maximizedbecause by a large amount of daylight drawn into the building throughthe windows largely decreases the artificial lighting energy consumptionwhile the cooling energy consumption slightly increases. However, eventhough maximum energy savings are achieved, visual comfort may not beattained because the glare index value increases greater than the visualcomfort threshold when the radiation set point value is greater than 105W/m². A third stage can include radiation levels that are greater than175 W/m². In this stage, an abrupt increase in the cooling energyconsumption occurs with no further decrease in the lighting energyconsumption, which results in the total energy consumption curvedrastically increasing due to an increase in the overall consumption ofthe building.

In some implementations, the lighting energy consumption for thebuilding 114 is reduced by 3% and end-use cooling energy consumption isreduced by 4% by controlling the electrochromic smart windows with anorth orientation with the solar control strategy at a radiation setpoint of 105 W/m². Also the total energy consumption of building isreduced by 3%. Table 11 shows a comparison between the solar controlstrategy and the glare control strategy for the windows of the buildinghaving a north orientation. As shown in Table 11, the solar controlstrategy may provide greater energy savings than the glare controlstrategy while still maintaining the visual comfort criteria.

TABLE 11 Solar solar Glare control Glare control control Energy Basecase 105 W/m² control (% Reduc- (% Reduc- consumption (kWh) (kWh) (kWh)tion) tion) Lighting 136,857 132,751 133,435 3 2.5 Cooling 1,587,1911,523,703 1,515,767 4 4.5 Total 2,174,093 2,108,870 2,108,870 3 2.7

For an east orientation of the building 114, the processing circuitry ofthe controller 102 can determine projected solar radiation levels at thewindows for each zone of the building 114 and can also calculate anamount of energy savings as well as a glare index for the windows ateach orientation of the building 114. In one implementation, at a solarradiation set point value of 100 W/m², the energy savings are increasedand the calculated glare index is less than the predetermined visualcomfort threshold for all zones of the building 114. FIG. 27 is anexemplary graph of monthly variations in glare index for solar controland glare control for windows having an east orientation, according tocertain embodiments. Maximum glare index values are plotted at the solarset point of 100 W/m² in order to show the visual comfort criteria isbeing achieved when the solar control strategy is applied to theelectrochromic smart windows.

FIG. 28 is an exemplary graph of lighting, cooling, and total energyconsumption for various solar radiation set points using the solarcontrol strategy for windows having a east orientation, according tocertain embodiments. As the solar radiation set point value increases,the amount of daylight entering the building 114 through the windowsincreases which results in a decrease in artificial lightingconsumption. Increasing the solar radiation set point value alsoincreases a cooling load. In some implementations, the lighting energyconsumption is reduced by 5% and the cooling energy consumption isreduced by 3% by controlling the electrochromic smart windows with aneast orientation with a solar control strategy at a radiation set pointof 100 W/m². As discussed previously with respect to the northorientation windows, in some implementations, the total energyconsumption curve can be divided into 3 stages associated with variousset point radiation levels.

Table 12 shows a comparison between the solar control strategy and theglare control strategy for the windows of the building having an eastorientation. As shown in Table 12, the solar control strategy mayprovide greater total energy savings than the glare control strategywhile still maintaining the visual comfort criteria.

TABLE 12 Solar solar Glare control Glare control control Energy BaseCase 100 W/m² control (% Reduc- (% Reduc- consumption (kWh) (kWh) (kWh)tion) tion) Lighting 136,857 130,000 131,376 5 4 Cooling 1,587,1911,539,561 1,531,646 3 3.5 Total 2,174,093 2,065,392 2,076,281 5 4.5

For a south orientation of the building 114, the processing circuitry ofthe controller 102 can determine projected solar radiation levels at thewindows for each zone of the building 114 and can also calculate anamount of energy savings as well as a glare index for the windows ateach orientation of the building 114. In one implementation, at a solarradiation set point value of 95 W/m², the energy savings are increasedand the calculated glare index is less than the predetermined visualcomfort threshold for all zones of the building 114. FIG. 29 is anexemplary graph of monthly variations in glare index for solar controland glare control for windows having a south orientation, according tocertain embodiments. Maximum glare index values are plotted at the solarset point of 95 W/m² in order to show the visual comfort criteria isbeing achieved when the solar control strategy is applied to theelectrochromic smart windows.

FIG. 30 is an exemplary graph of lighting, cooling, and total energyconsumption for various solar radiation set points using the solarcontrol strategy for windows having a south orientation, according tocertain embodiments. As the solar radiation set point value increases,the amount of daylight entering the building 114 through the windowsincreases which results in a decrease in artificial lightingconsumption. Increasing the solar radiation set point value alsoincreases a cooling load. In some implementations, the lighting energyconsumption is reduced by 7% and the cooling energy consumption isreduced by 2% by controlling the electrochromic smart windows with thesouth orientation with a solar control strategy at a radiation set pointof 95 W/m². Also the total energy consumption of building is reduced by7%. As discussed previously with respect to the north orientationwindows, in some implementations, the total energy consumption curve canbe divided into 3 stages associated with various set point radiationlevels.

Table 13 shows a comparison between the solar control strategy and theglare control strategy for the windows of the building having a southorientation. As shown in Table 13, the solar control strategy mayprovide greater total energy savings than the glare control strategywhile still maintaining the visual comfort criteria.

TABLE 13 Solar solar Glare control Glare control control Energy BaseCase 95 W/m² control (% Reduc- (% Reduc- consumption (kWh) (kWh) (kWh)tion) tion) Lighting 136,857 127,277 128,645 7 6 Energy Cooling1,587,191 1,555,447 1,547,511 2 2.5 Total 2,174,093 2,021,906 2,032,7767 6.5

For a west orientation of the building 114, the processing circuitry ofthe controller 102 can determine projected solar radiation levels at thewindows for each zone of the building 114 and can also calculate anamount of energy savings as well as a glare index for the windows ateach orientation of the building 114. In one implementation, at a solarradiation set point value of 100 W/m², the energy savings are increasedand the calculated glare index is less than the predetermined visualcomfort threshold for all zones of the building 114. FIG. 31 is anexemplary graph of monthly variations in glare index for solar controland glare control for windows having the west orientation, according tocertain embodiments. Maximum glare index values are plotted at the solarset point of 100 W/m² in order to show the visual comfort criteria isbeing achieved when the solar control strategy is applied to theelectrochromic smart windows.

FIG. 32 is an exemplary graph of lighting, cooling, and total energyconsumption for various solar radiation set points using the solarcontrol strategy for windows having the west orientation, according tocertain embodiments. As the solar radiation set point value increases,the amount of daylight entering the building 114 through the windowsincreases which results in a decrease in artificial lightingconsumption. Increasing the solar radiation set point value alsoincreases a cooling load. In some implementations, the lighting energyconsumption is reduced by 5% and the cooling energy consumption isreduced by 3% by controlling the electrochromic smart windows with thesouth orientation with a solar control strategy at a radiation set pointof 100 W/m². Also the total energy consumption of building is reduced by5%. As discussed previously with respect to the north orientationwindows, in some implementations, the total energy consumption curve canbe divided into 3 stages associated with various set point radiationlevels.

Table 14 shows a comparison between the solar control strategy and theglare control strategy for the windows of the building having the westorientation. As shown in Table 14, the solar control strategy mayprovide greater total energy savings than the glare control strategywhile still maintaining the visual comfort criteria.

TABLE 14 Solar solar Glare Energy control Glare control control FlowBase case 100 W/m² control (% Reduc- (% Reduc- consumption (kWh) (kWh)(kWh) tion) tion) Lighting 136,857 130,014 131,382 5 4 cooling 1,587,1911,539,575 1,531,639 3 3.5 Total 2,174,093 2,065,388 2,076,285 5 4.5

Table 15 illustrates shows energy savings for the electrochromic smartwindows controlled with the solar control strategy when visual comfortis not accounted for in various orientations. By using the solar controlstrategy without accounting for visual comfort, the windows having asouth orientation provided a higher amount of energy savings than thewindows having north, east, or west orientations.

TABLE 15 Maximum energy savings Energy savings (No visual comfort)(visual comfort) Orientation Lighting Cooling Total Lighting CoolingTotal NORTH 7 3 4 3 4 3 EAST 6.5 2.5 5.5 5 3 5 SOUTH 8.5 1.7 8 7 2 7WEST 6.5 2.5 5.5 5 3 5

The controller 102 can also control the amount of daylight passingthrough the electrochromic smart windows based on a window-to-wall ratio(WWR) for the zones of the building. For small window areas, there maybe a small reduction in energy consumption when daylight entering thewindows is integrated with artificial lighting. When the electrochromicsmart windows are controlled with the solar control strategy, the totalenergy consumption at first decreases and then increases for as the WWRincreases for each building orientation. For example, window size canhave two major impacts on the energy performance of the building. As thewindow size get larger, more lighting energy is saved. However coolingenergy is increases.

FIG. 33 is an exemplary graph of energy consumption based on window towall ratio (WWR), according to certain embodiments. Admitting highamount of daylight may increase the heat gain in the building 114, whichin turn increase the cooling energy consumption. Also, the total energyconsumption of the building 114 with smaller WWR values may decrease dueto the decrease in the lighting energy consumption. Between 50-70% WWR,the lighting energy savings reaches a saturation point where maximumenergy savings may be achieved. WWRs greater 70% may provide anincreased amount of solar radiation through the windows which alsoincreases the cooling energy consumption, resulting in increased totalenergy consumption. Therefore, in some implementations, energy savingsmay be highest when the WWR is between 50% and 70%.

When taking into account the radiation set points discussed previouslywith respect to the north, east, south, and west orientations, the solarcontrol strategy provides a reduction in artificial lighting energyconsumption by 20%, a reduction in cooling energy consumption by 121%,and a reduction in total building energy consumption by 20%. FIG. 34 isan exemplary graph of monthly variations in daylight factor associatedwith the solar control strategy, according to certain embodiments. Forexample, the average Daylight factor (%) plotted on the graphs indicatesan amount of sunlight that enters the building 114 through the windowsand is used by the controller 102 to determine the amount of artificiallighting to provide to the zones of the building.

The solar control strategy can also be used by the controller 102 tocontrol the operation of automated venetian blinds that are installed onthe windows of the building 114. The amount of shading provided by theblinds is controlled by a position or angle of rotation of the blinds,which can be determined based on climactic criteria. Depending on theseason, solar radiation that produces heat is either blocked or let in.Thermo sensors can installed at each of the windows to measure an amountof radiation falling on the windows, and the sensor data from thesensors can be used by the controller 102 to determine the amount ofshading provided by the blinds. In some implementations, the WWR for thebuilding 114 is 50%. In one example, the automated venetian blinds canbe used as an interior shading double glazed clear glass, and thecontroller 102 can modify the amount of shading based on the radiationset point values discussed previously for each orientation. For example,for the automated venetian blinds in the north orientation, the solarradiation set point value is set at 105 W/m². Similarly, for the eastand west orientations, the solar radiation set point value is 100 W/m².For windows with a south orientation, the solar radiation value is 95W/m². FIG. 35 shows the monthly variation in the maximum glare index thebuilding 114 with electrochromic smart windows and automated venetianblinds operated with the solar control strategy in all the orientations.For both electrochromic smart windows and automated venetian blinds, thevisual comfort criteria are achieved.

Table 16 shows a comparison between solar control of the electrochromicsmart windows and windows configured with automated venetian blind basedon the energy performance. The electrochromic smart windows provide anenergy savings of 20% in total building energy consumption, whereas theautomated venetian blind provide an energy savings of 16% for totalbuilding energy consumption. The savings from both smart windowstechnologies can be used to make the design sustainable and save themoney for the building owner.

TABLE 16 Percentage Reduction solar control by using Venetian strategyBlinds Energy Consumption (%) (%) Lighting Energy 20 18 cooling energy12 17 Total Energy 20 16

FIG. 36 is an exemplary graph of monthly variations in daylight factorassociated with controlling the automated venetian blinds with the solarcontrol strategy, according to certain embodiments. For example, theaverage Daylight factor (%) plotted on the graphs indicates an amount ofsunlight that enters the building 114 through the windows and is used bythe controller 102 to determine the amount of artificial lighting toprovide to the zones of the building.

FIG. 37 is a target illuminance control process 3700, according tocertain embodiments. The target illuminance control process 3700 is oneimplementation of step S308 of the smart window control process 300.

At step S3702, the processing circuitry of the controller 102 determinesa target illuminance for each zone of the building 114. The targetilluminance corresponds to a total amount of illumination from bothnatural (e.g., daylight) and artificial (e.g., lighting systems)lighting sources. In one implementation, the target illuminance for thezones of the building 114 is 500 Lux. In other implementations, eachzone can have an assigned target illuminance based on a functionalityassociated with the zone. For example, hallways and stairways of abuilding may have a lower target illuminance than general work spaces ofthe building 114, such as 300 Lux.

At step S3704, the processing circuitry determines control trigger andoperating points based on the light control strategy being implemented.As discussed previously, each of the lighting control strategiesincludes various set points associated with achieving energy savingswhile maintaining visual comfort criteria. For example, the solarcontrol strategy includes radiation set point values associated witheach building orientation (north, east, south, and west).

In addition, the daylight control strategy uses daylighting illuminationas a valid control trigger for the electrochromic smart windows.Illumination sensors that can include photodiode sensors can detect anamount of lighting inside the building. The transmittance of the glazingon the windows can be modified to just meet a daylight illuminance setpoint at one or more of the daylighting interior illumination sensors.With a solar control strategy, shading is applied to the windows when abeam plus diffuse solar radiation incident on the window exceeds apredetermined radiation set point value. With a glare control strategy,the transmittance of the glazing on the windows can be modified when atotal daylight glare index for a building zone from all of the exteriorwindows in the zone exceeds a predetermined glare index threshold in thedaylighting input for zone.

At step S3706, the controller 102 issues control signals to modify theparameters of the electrochromic smart windows and/or automated venetianblinds. For example, the controller 102 can control an operating voltageof electrochromic windows to modify an amount of shading provided by thewindows in order to allow a predetermined amount of daylight to enterthe building through the windows to meet the operational set points. Thecontroller 102 can also control an amount of shading provided byautomated blinds that are installed on an interior surface of thewindows.

At step S3708, the controller 102 controls the artificial lightingsystems of the building 114 to compensate for an illumination deficitbetween the target illuminance and the amount of light transmittedthrough the windows. In some implementations, the illumination deficitis equal to the target illuminance minus the amount of daylight enteringthe building 114 through the electrochromic windows with a predeterminedamount of shading applied based on the light control strategy. Thecontroller 102 issues control signals to modify an amount of artificiallighting provided by the lighting systems of the building 114 so thatthe target illuminance is met. In some implementations, interiorilluminance sensors detect the daylight entering the building 114through the windows, and the controller 102 issues a control signal tomodify the fractional input power of artificial lighting in discretesteps until the target illuminance is achieved.

A hardware description of an exemplary server 102 for performing one ormore of the embodiments described herein is described with reference toFIG. 38. In addition, the hardware described by FIG. 38 can also applyto the computer 110, mobile device 112, as well as circuitry associatedwith the smart windows of the building 114. When the server 102,computer 110, and/or mobile device 112 are programmed to perform theprocesses related to video editing described herein, the server 102,computer 110, and/or mobile device 112 becomes a special purpose device.Implementation of the processes of the smart window control system 100on the hardware described herein improves the efficiency of determiningan amount of sunlight that passes through windows, controlling an amountof shading provided by the windows, and controlling operation of otherbuilding systems to increase an amount of energy savings. In addition,the processes described herein can also be applied to other types ofsmart windows and/or lighting systems.

The server 102 includes a CPU 3800 that perform the processes describedherein. The process data and instructions may be stored in memory 3802.These processes and instructions may also be stored on a storage mediumdisk 3804 such as a hard drive (HDD) or portable storage medium or maybe stored remotely. Note that each of the functions of the describedembodiments may be implemented by one or more processing circuits. Aprocessing circuit includes a programmed processor, as a processorincludes circuitry. A processing circuit/circuitry may also includedevices such as an application specific integrated circuit (ASIC) andconventional circuit components arranged to perform the recitedfunctions. The processing circuitry can be referred to interchangeablyas circuitry throughout the disclosure. Further, the claimedadvancements are not limited by the form of the computer-readable mediaon which the instructions of the inventive process are stored. Forexample, the instructions may be stored on CDs, DVDs, in FLASH memory,RAM, ROM, PROM, EPROM, EEPROM, hard disk or any other informationprocessing device with which the server 102 communicates, such as themobile device 112 and/or the computer 110.

Further, the claimed advancements may be provided as a utilityapplication, background daemon, or component of an operating system, orcombination thereof, executing in conjunction with CPU 3800 and anoperating system such as Microsoft Windows, UNIX, Solaris, LINUX, AppleMAC-OS and other systems known to those skilled in the art.

CPU 3800 may be a Xenon or Core processor from Intel of America or anOpteron processor from AMD of America, or may be other processor typesthat would be recognized by one of ordinary skill in the art.Alternatively, the CPU 3800 may be implemented on an FPGA, ASIC, PLD orusing discrete logic circuits, as one of ordinary skill in the art wouldrecognize. Further, CPU 3800 may be implemented as multiple processorscooperatively working in parallel to perform the instructions of theinventive processes described above.

The server 102 in FIG. 38 also includes a network controller 3806, suchas an Intel Ethernet PRO network interface card from Intel Corporationof America, for interfacing with network 104. As can be appreciated, thenetwork 104 can be a public network, such as the Internet, or a privatenetwork such as an LAN or WAN network, or any combination thereof andcan also include PSTN or ISDN sub-networks. The network 104 can also bewired, such as an Ethernet network, or can be wireless such as acellular network including EDGE, 3G and 4G wireless cellular systems.The wireless network can also be Wi-Fi, Bluetooth, or any other wirelessform of communication that is known.

The server 102 further includes a display controller 3808, such as aNVIDIA GeForce GTX or Quadro graphics adaptor from NVIDIA Corporation ofAmerica for interfacing with display 3810 of the server 102 and thecomputer 110, such as an LCD monitor. A general purpose I/O interface3812 at the server 102 interfaces with a keyboard and/or mouse 3814 aswell as a touch screen panel 3816 on or separate from display 3810.General purpose I/O interface 3812 also connects to a variety ofperipherals 3818 including printers and scanners.

A sound controller 3820 is also provided in the server 102, such asSound Blaster X-Fi Titanium from Creative, to interface withspeakers/microphone 3822 thereby providing sounds and/or music.

The general purpose storage controller 3824 connects the storage mediumdisk 3804 with communication bus 3826, which may be an ISA, EISA, VESA,PCI, or similar, for interconnecting all of the components of the server102. A description of the general features and functionality of thedisplay 3810, keyboard and/or mouse 3814, as well as the displaycontroller 3808, storage controller 3824, network controller 3806, soundcontroller 3820, and general purpose I/O interface 3812 is omittedherein for brevity as these features are known.

The exemplary circuit elements described in the context of the presentdisclosure may be replaced with other elements and structureddifferently than the examples provided herein. Moreover, circuitryconfigured to perform features described herein may be implemented inmultiple circuit units (e.g., chips), or the features may be combined incircuitry on a single chipset, as shown on FIG. 39.

FIG. 39 shows a schematic diagram of a data processing system, accordingto certain embodiments, for performing the smart window control process300, the zone/building development process 700, the control strategydetermination process 2000, and/or the target illuminance controlprocess 3700. The data processing system is an example of a computer inwhich code or instructions implementing the processes of theillustrative embodiments may be located.

In FIG. 39, data processing system 3900 employs a hub architectureincluding a north bridge and memory controller hub (NB/MCH) 3925 and asouth bridge and input/output (I/O) controller hub (SB/ICH) 3920. Thecentral processing unit (CPU) 3930 is connected to NB/MCH 3925. TheNB/MCH 3925 also connects to the memory 3945 via a memory bus, andconnects to the graphics processor 3950 via an accelerated graphics port(AGP). The NB/MCH 3925 also connects to the SB/ICH 3920 via an internalbus (e.g., a unified media interface or a direct media interface). TheCPU Processing unit 3930 may contain one or more processors and even maybe implemented using one or more heterogeneous processor systems.

For example, FIG. 40 shows one implementation of CPU 3930. In oneimplementation, the instruction register 4038 retrieves instructionsfrom the fast memory 4040. At least part of these instructions arefetched from the instruction register 4038 by the control logic 4036 andinterpreted according to the instruction set architecture of the CPU3930. Part of the instructions can also be directed to the register4032. In one implementation the instructions are decoded according to ahardwired method, and in another implementation the instructions aredecoded according a microprogram that translates instructions into setsof CPU configuration signals that are applied sequentially over multipleclock pulses. After fetching and decoding the instructions, theinstructions are executed using the arithmetic logic unit (ALU) 4034that loads values from the register 4032 and performs logical andmathematical operations on the loaded values according to theinstructions. The results from these operations can be feedback into theregister and/or stored in the fast memory 4040. According to certainimplementations, the instruction set architecture of the CPU 3930 canuse a reduced instruction set architecture, a complex instruction setarchitecture, a vector processor architecture, a very large instructionword architecture. Furthermore, the CPU 3930 can be based on the VonNeuman model or the Harvard model. The CPU 3930 can be a digital signalprocessor, an FPGA, an ASIC, a PLA, a PLD, or a CPLD. Further, the CPU3930 can be an x86 processor by Intel or by AMD; an ARM processor, aPower architecture processor by, e.g., IBM; a SPARC architectureprocessor by Sun Microsystems or by Oracle; or other known CPUarchitecture.

Referring again to FIG. 39, the data processing system 3900 can includethat the SB/ICH 3920 is coupled through a system bus to an I/O Bus, aread only memory (ROM) 3956, universal serial bus (USB) port 3964, aflash binary input/output system (BIOS) 3968, and a graphics controller3958. PCI/PCIe devices can also be coupled to SB/ICH YYY through a PCIbus 3968.

The PCI devices may include, for example, Ethernet adapters, add-incards, and PC cards for notebook computers. The Hard disk drive 3960 andCD-ROM 3966 can use, for example, an integrated drive electronics (IDE)or serial advanced technology attachment (SATA) interface. In oneimplementation the I/O bus can include a super I/O (SIO) device.

Further, the hard disk drive (HDD) 3960 and optical drive 3966 can alsobe coupled to the SB/ICH 3920 through a system bus. In oneimplementation, a keyboard 3970, a mouse 3972, a parallel port 3978, anda serial port 3976 can be connected to the system bust through the I/Obus. Other peripherals and devices that can be connected to the SB/ICH3920 using a mass storage controller such as SATA or PATA, an Ethernetport, an ISA bus, a LPC bridge, SMBus, a DMA controller, and an AudioCodec.

Moreover, the present disclosure is not limited to the specific circuitelements described herein, nor is the present disclosure limited to thespecific sizing and classification of these elements. For example, theskilled artisan will appreciate that the circuitry described herein maybe adapted based on changes on battery sizing and chemistry, or based onthe requirements of the intended back-up load to be powered.

The functions and features described herein may also be executed byvarious distributed components of a system. For example, one or moreprocessors may execute these system functions, wherein the processorsare distributed across multiple components communicating in a network.The distributed components may include one or more client and servermachines, which may share processing in addition to various humaninterface and communication devices (e.g., display monitors, smartphones, tablets, personal digital assistants (PDAs)). The network may bea private network, such as a LAN or WAN, or may be a public network,such as the Internet. Input to the system may be received via directuser input and received remotely either in real-time or as a batchprocess. Additionally, some implementations may be performed on modulesor hardware not identical to those described. Accordingly, otherimplementations are within the scope that may be claimed.

The above-described hardware description is a non-limiting example ofcorresponding structure for performing the functionality describedherein. In other alternate embodiments, processing features according tothe present disclosure may be implemented and commercialized ashardware, a software solution, or a combination thereof. Moreover,instructions corresponding to the smart window control process 300, thezone/building development process 700, the control strategydetermination process 2000, and/or the target illuminance controlprocess 3700 in accordance with the present disclosure could be storedin a thumb drive that hosts a secure process.

According to certain embodiments, the smart window control system 100provides the processing power to adaptively modify the amount of shadingprovided by electrochromic smart windows and/or automated venetianblinds based on an amount of sunlight entering the building 114 throughthe windows as well as based on energy savings and visual comfortcriteria. The processes described herein can also be applied to othertechnical fields that involve adapting operations of building systemsbased on external environmental factors.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of this disclosure. For example, preferableresults may be achieved if the steps of the disclosed techniques wereperformed in a different sequence, if components in the disclosedsystems were combined in a different manner, or if the components werereplaced or supplemented by other components. The functions, processesand algorithms described herein may be performed in hardware or softwareexecuted by hardware, including computer processors and/or programmablecircuits configured to execute program code and/or computer instructionsto execute the functions, processes and algorithms described herein.Additionally, an implementation may be performed on modules or hardwarenot identical to those described. Accordingly, other implementations arewithin the scope that may be claimed.

1-20. (canceled) 21: A smart window control system, comprising: one or more artificial lighting systems disposed inside a building, a first sensor disposed on the exterior of one or more electrochromic smart windows to measure an amount of direct solar radiation, a second sensor disposed on the exterior of the one or more electrochromic smart windows to measure an amount of diffuse solar radiation, and a smart window control device comprising: a controller having a processor with circuitry configured to: establish a representative model of a plurality of building periphery zones and a single building core zone based on occupancy, construction, lighting, or cooling properties of the building, wherein all of the building periphery zones have an equal window-to-wall ratio, implement a lighting control strategy for the building periphery zones and the building core zone based on the representative model or one or more user preferences input at a first user interface screen of an external device, control automatic operations of one or more electrochromic smart windows by varying a voltage applied to a stack of electrochromic coating layers, or artificial lighting systems by modifying a fractional input power in discrete steps based on trigger points associated with the lighting control strategy and measures of the direct solar radiation and the diffuse solar radiation measured at the one or more electrochromic smart windows by the first and second sensors, respectively, and radiation set point values associated with each building orientation, control automatic operations of the one or more or artificial lighting systems by modifying a fractional input power in discrete steps based on trigger points associated with the lighting control strategy and radiation set point values associated with each building orientation, and determine with the circuitry a performance level of the lighting control strategy for the building periphery zones and the building core zone based on one or more predetermined financial metrics that include a comparison of total building energy consumption to a threshold, wherein the circuitry is further configured to determine a comfort score and an energy savings score indicating a relative importance of visual comfort and energy savings for the building periphery zones and the building core zone based on the representative model of the building periphery zones and the building core zone or the one or more user preferences, the circuitry is further configured to implement a daylight control strategy as the lighting control strategy when the energy savings score is greater than an energy savings threshold or the comfort score is lower than a visual comfort threshold, and the circuitry is further configured to implement a solar control strategy or a glare control strategy as the lighting control strategy when the energy savings score is less than or equal to an energy savings threshold and the comfort score is greater than or equal to a visual comfort threshold, wherein the predetermined financial metrics include a predetermined payback period associated one or more building components based on a current energy costs, price of the one or more building components, and one or more financial health attributes of a building, and wherein the circuitry is further configured to output a warning to the external device when an amount of energy savings associated with the one or more smart windows over a predetermined period of time does not meet the predetermined payback period associated with the one or more building components. 22: The system of claim 21, wherein the circuitry is further configured to implement the daylight control strategy, the glare control strategy, or the solar control strategy based on the representative model of the building periphery zones and the building core zone or the one or more user preferences. 23: The system of claim 22, wherein the circuitry is further configured to control the automatic operations of the one or more smart windows to achieve a predetermined daylight illuminance sensor set point when the daylight control strategy is implemented. 24: The system of claim 22, wherein the circuitry is further configured to control the automatic operations of the one or more electrochromic smart windows to achieve a predetermined glare index set point when the glare control strategy is implemented. 25: The system of claim 22, wherein the circuitry is further configured to control the automatic operations of the one or more electrochromic smart windows to achieve a predetermined solar radiation set point when the solar control strategy is implemented. 26: The system of claim 21, wherein the circuitry is further configured to determine an impact weighting factor associated with the first and second sensors based on at least one of sensor value, time of day, or time of year. 27: The system of claim 21, wherein the circuitry is further configured to determine an illumination deficit for the building periphery zones and the building core zone corresponding to a difference between a target illuminance and an amount of daylight illuminance from the one or more electrochromic smart windows. 